Moldex 6684 SparkPlugs Review: Uncorded — 50-pair jar NRR 33
WC Safety Editorial Verdict: 4.2/5
The Moldex 6684 jar packages the same firm NRR 33 dual-layer SparkPlugs foam as the boxed Moldex 6604 SparkPlugs, but in an open-access jar built for point-of-use stocking at secondary workstations, tool carts, and supervisor stations where a wall dispenser is impractical. It earns its score on deployment convenience and per-pair economy rather than any acoustic edge — protection is identical to every other SparkPlug, so the jar is the right buy only when accessible-but-unwrapped dispensing suits your environment (it is wrong for food, pharma, or oily/dusty areas). For canal comfort over raw blocking, the softer Moldex 6800 Pura-Fit is the better-tolerated NRR 33 alternative.
Moldex 6684 SparkPlugs Refill Jar Review: NRR 35 Uncorded 500-Pair Bulk Jar for Workstation Dispensing
The Moldex 6684 SparkPlugs Refill Jar is the 500-pair open-access workstation jar format — loose unwrapped NRR 35 SparkPlugs in a lidded jar for secondary workstation and toolbox deployment. For the primary bulk box format, see the Moldex 6604 (200-pair box). For corded variants, see the Moldex 6654 (corded) or Moldex 6615 (metal-detectable corded). For softer foam at NRR 33, see the Moldex 6800 Pura-Fit.
Editorial Verdict — 4.2 / 5
The 6684 jar solves a specific deployment problem: how to make NRR 35 earplugs available at secondary workstations, supervisor stations, and areas too small or too temporary for a wall-mounted dispenser. The 500-pair capacity makes it economical for long-run deployments, and the open-access jar means workers don't need to go to a central dispenser to get hearing protection during a noise exposure. Same NRR 35 dual-layer SparkPlugs foam as the 6604 bulk box.
Quick-Reference Specs: Moldex 6684 SparkPlugs Refill Jar
| Specification | Detail |
|---|---|
| Model | 6684 |
| NRR | 35 dB (ANSI/ASA S3.19) |
| Format | Uncorded, open-access lidded jar |
| Construction | Dual-layer SparkPlugs foam — same as 6604 |
| Pack Size | 500 pairs per jar |
| Wrapper | Unwrapped — loose plugs in jar |
| OSHA Standard | 29 CFR 1910.95 (Hearing Conservation) |
| Typical Use | Secondary workstations, toolboxes, supervisor stations |
| Country of Origin | USA |
Jar Format vs. Bulk Box vs. Dispenser: Choosing the Right Deployment
Effective hearing conservation programs under OSHA 29 CFR 1910.95 require that hearing protection be readily accessible — workers should not have to walk significant distances or interrupt work to obtain earplugs. The deployment format determines how accessible hearing protection is at any given workstation:
| Format | Product | Capacity | Best Deployment |
|---|---|---|---|
| Wall-mount dispenser | Moldex EcoStation + 6604 bulk | 500+ pairs | Primary high-traffic areas; large workforces |
| Bulk box | 6604 (200-pair) | 200 pairs | Primary workstations with box storage; supervisor kits |
| Workstation jar | 6684 (500-pair jar) | 500 pairs | Secondary workstations, toolboxes, no dispenser available |
| Corded individual | 6654 (100-pair box) | 100 pairs | FOD-mandate or cord-mandate individual issue |
The 6684 jar fills the secondary workstation gap. A production line may have a primary wall dispenser at the main entry point, but a worker at a secondary station or in a maintenance bay needs earplugs available where they work — not at the other end of the facility. The 6684 jar provides 500 pairs in a compact, stable container that sits on a workbench, tool cart, or shelf without requiring permanent installation.
Why 500 Pairs in a Jar: Economic and Operational Advantages
The 500-pair capacity represents significant per-pair economies over the 200-pair boxed format. For high-turnover workstations where multiple workers go through earplugs daily, the 6684 reduces restocking frequency. The open-access design — workers take plugs directly from the jar — eliminates the per-pair wrapper waste associated with individually wrapped bulk-box products, which also reduces per-pair cost.
The trade-off versus a dispenser: the open-access jar allows anyone to take multiple pairs, and there is no dispense-count metering. For facilities tracking hearing protection consumption as part of OSHA 29 CFR 1910.95(d)(3) program evaluation, metered dispensers provide better consumption data. For lower-oversight secondary locations, the 6684's simplicity and accessibility outweigh metering advantages.
NRR 35 Performance: Same Foam as 6604
The foam insert in the 6684 is identical to that in the 6604 bulk box — dual-layer SparkPlugs construction with NRR 35. Workers switching between workstations where one uses a dispenser with 6604 bulk and another uses the 6684 jar will experience identical hearing protection performance. The jar format does not affect NRR.
Under NIOSH 50% derating, NRR 35 provides approximately 17.5 dB effective noise reduction. Using OSHA's formula ((35-7)/2), the result is 14 dB. At a workstation generating 104 dBA TWA, the OSHA-formula-derated 6684 reduces effective exposure to 90 dBA — exactly at the PEL. For consistent compliance margin, NIOSH derating guidance should also be reviewed and documented in the written hearing conservation program.
Maintaining the Jar: Hygiene and Contamination Considerations
Open-access jars raise hygiene questions that don't apply to individually wrapped earplugs. Best practices for the 6684 jar:
- Keep the lid closed when not in use — dust, debris, and moisture contaminate open foam and can irritate the ear canal
- Replace the jar when visual contamination (oil, dirt, metal filings) is evident — contaminated earplugs should not be inserted in the ear
- Do not allow workers to return used or touched earplugs to the jar — the jar is a one-way dispense system, not a shared container
- In food processing environments, the 6684 is NOT appropriate — use individually wrapped pairs or the metal-detectable 6615 to maintain HACCP traceability
- In greasy or oily environments, position the jar away from machinery that generates mist or splatter — oil-contaminated earplugs are difficult to roll and may not expand correctly in the canal
OSHA 29 CFR 1910.95 Hearing Conservation: Deployment Requirements
OSHA 29 CFR 1910.95(i)(2) requires that hearing protectors be available to all employees exposed at or above the action level (85 dBA TWA) at no cost. The 6684 jar placed at the workstation satisfies the availability requirement. Employers must also ensure that workers are trained to use hearing protectors correctly — OSHA 29 CFR 1910.95(k)(3)(iii) requires training on the purpose and use of hearing protectors, including correct insertion technique for foam earplugs.
For complete hearing protection program support including audiometric testing equipment, earmuffs, and hearing conservation program documentation, browse the WC Safety hearing protection collection.
Frequently Asked Questions: Moldex 6684 SparkPlugs Jar
Q: Is the foam in the 6684 jar the same as the 6604 bulk box?
A: Yes. The 6684 contains the same NRR 35 dual-layer SparkPlugs foam as the 6604. The only difference is the packaging format — loose plugs in an open-access jar vs. individually wrapped pairs in a bulk box.
Q: How many pairs does the 6684 jar hold?
A: 500 pairs (1,000 individual earplugs). The 500-pair capacity makes it economical for high-turnover workstations and reduces restocking frequency compared to the 200-pair bulk box.
Q: Can the 6684 jar be used to refill Moldex EcoStation dispensers?
A: No. Moldex EcoStation dispensers use specific refill cartridges — loose jar earplugs cannot be loaded into the EcoStation dispenser mechanism. The 6684 jar is a standalone workstation dispense format, not a refill for wall-mounted dispensers. For EcoStation refills, use the appropriate Moldex EcoStation refill cartridge.
Q: Is the open-jar format hygienic?
A: When the jar is kept lidded between uses and workers do not return used or handled earplugs to the jar, hygiene is adequate for most industrial environments. The jar is not appropriate for food processing, pharmaceutical clean rooms, or sterile environments where contamination controls require individually wrapped or traceable PPE.
Q: What is the per-pair cost advantage of the 6684 jar vs. the 6604 bulk box?
A: The 6684 provides 500 pairs vs. 200 pairs in the 6604, typically at a lower per-pair cost. The savings come from the unwrapped format (no individual wrapper cost) and the bulk quantity. For workstations with high daily usage, the 6684 jar provides better economics over the 6604 box. Compare current pricing at WC Safety.
Q: Can the 6684 jar be used in food processing environments?
A: No. The 6684 does not contain metal-detectable compound and the open-jar format does not provide HACCP traceability for individual pairs. For food processing with X-ray or metal detection requirements, use the 6615 metal-detectable corded.
Q: What NRR does the 6684 provide?
A: NRR 35 per ANSI/ASA S3.19 — identical to the uncorded 6604 and corded 6654. Under NIOSH 50% derating, effective noise reduction is approximately 17.5 dB. Under the OSHA formula ((NRR-7)/2), effective reduction is 14 dB.
Q: Does OSHA require that earplugs be individually wrapped?
A: OSHA 29 CFR 1910.95 does not require individually wrapped hearing protection. The standard requires that protectors be available and that workers be trained to use them properly. Open-jar dispensing is a permissible format under OSHA's hearing conservation standard for most industrial applications.
Q: How should the 6684 jar be positioned at workstations?
A: Position the jar at a location accessible to workers before they enter the noise hazard zone — at the workstation entry, on the tool cart, or at the bench where workers prepare for the task. The jar should be at arm's reach without requiring workers to enter or re-enter the noise area to obtain hearing protection. Keep the lid closed when not actively dispensing to prevent contamination.
Q: What insertion technique should workers use with the 6684 SparkPlugs?
A: Same as all SparkPlugs: roll the firm outer skin between thumb and forefinger to compress the plug thin; pull the pinna up and back with the opposite hand; insert deeply while maintaining the pull; hold in place for 30–60 seconds while the foam expands. Post insertion instructions near the jar as a visual reminder — OSHA 29 CFR 1910.95(k) requires training on correct use.
Q: Is the 6684 appropriate for construction sites?
A: Yes — construction operations subject to OSHA 29 CFR 1926.52 noise requirements can use the 6684 jar at tool trailers, site offices, or staging areas. For mobile crews moving between high-noise tasks, the 6604 individually wrapped pairs may be more practical since workers can carry a pair in their pocket. The 6684 jar works best at fixed locations.
Q: How often should the 6684 jar be refilled or replaced?
A: Replace or refill when the jar is visually less than one-quarter full — running low on available plugs can discourage workers from taking hearing protection if they feel supplies are scarce. Replace the entire jar (not just refill it) if contamination is visible — oil, grease, metal filings, or moisture inside the jar. The jar itself is reusable until the lid seal is compromised or the jar is damaged.
Q: Can the 6684 jar be used for audiometric testing program compliance documentation?
A: The 6684 jar provides hearing protection as required by OSHA 29 CFR 1910.95(i). For program documentation, record the model (6684 SparkPlugs NRR 35) and the workstations where jars are deployed. The open-access format does not meter usage — if consumption tracking is needed for program evaluation, metered dispensers provide better data. The 6684 jar satisfies the hearing protector provision requirement regardless of metering capability.
Q: Does the 6684 jar satisfy ANSI/ASA S12.6 fit-testing requirements?
A: ANSI/ASA S12.6 is a standard for earplug fit testing (field attenuation estimation systems like 3M's E-A-Rfit). The 6684 SparkPlugs NRR 35 can be fit-tested using these systems to verify individual worker fit and actual attenuation. Workers who achieve passing fit scores on the SparkPlugs can document their actual attenuation level, which may be higher than the labeled NRR under the NIOSH field study that informs the 50% derating recommendation.
Q: Where can I buy the Moldex 6684 SparkPlugs Refill Jar?
A: Available at WC Safety in the 500-pair jar, or check Check Price on Amazon → for price comparison. Browse the full hearing protection collection at WC Safety for all SparkPlugs formats and Moldex earplug dispensers.
Disclosures & editorial standards
WC Safety participates in the Amazon Services LLC Associates Program. Outbound Amazon links are affiliate links. We accept no manufacturer payment, sponsorship, or product samples. This content is not medical, legal, or regulatory advice. Safety equipment selection is governed by applicable OSHA standards and your facility's safety program.
WC Safety participates in the Amazon Services LLC Associates Program. Outbound Amazon links are affiliate links. We accept no manufacturer payment, sponsorship, or product samples. This content is not medical, legal, or regulatory advice. Safety equipment selection is governed by applicable OSHA standards and your facility's safety program.
Pros & Cons
Pros
- Same firm NRR 33 dual-layer SparkPlugs foam as the boxed 6604 and corded 6654 — no acoustic penalty for the jar format
- Open-access jar puts hearing protection at arm's reach at secondary workstations, tool carts, and supervisor stations with no dispenser to mount
- Bulk jar quantity with unwrapped loose plugs drives down per-pair cost versus individually wrapped boxes
- Firm SparkPlugs skin rolls down tightly for confident, deep insertion in larger or hard-to-seal ear canals
- Uncorded format avoids cord snag in machinery-light fixed-station work
- Reusable lidded jar sits stably on a bench without permanent installation
Cons
- Open jar offers no contamination barrier — wrong for food processing, pharma, clean rooms, or oily/dusty environments where wrappers or metal-detectable plugs are required
- No dispense metering, so the jar gives you no consumption data for hearing-conservation program evaluation
- Firmer SparkPlugs foam is less forgiving on small or sensitive ear canals than softer Pura-Fit or Softies
- Uncorded plugs are easy to drop and lose between uses where a corded 6654 would stay tethered
- NRR 33 is a lab number — real-world protection after NIOSH/OSHA derating is far lower and must be planned for
Who It's For
Buy it if:
- Safety managers stocking hearing protection at fixed secondary workstations, maintenance bays, or tool cribs without a wall dispenser
- High-traffic stations that burn through plugs daily and benefit from bulk jar economy and less frequent restocking
- Workers who prefer a firm, deep-seating foam plug and need a reliable seal in larger canals
- Facilities standardizing on SparkPlugs NRR 33 across boxed, corded, and jar formats for consistent attenuation
- Crews wanting grab-and-go uncorded plugs at a fixed bench rather than carried in a pocket
Look elsewhere if:
- Food, beverage, or pharmaceutical operations needing wrapped or metal-detectable plugs for HACCP traceability — choose the 6615 metal-detectable instead
- Programs that must track per-worker hearing-protector consumption, where a metered dispenser is required
- Workers with small or sensitive ear canals who find firm SparkPlugs foam uncomfortable — softer Pura-Fit or Softies fit better
- Mobile crews moving between high-noise tasks who are better served by corded or individually wrapped pairs
Related Resources
- foam ear plugs
- hearing protection
- nrr 33 ear plugs
- reusable earplugs
- disposable ear plugs
- what is nrr noise reduction rating explained
- best foam ear plugs
- highest nrr ear plugs
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- how to insert foam earplugs
- how to calculate the nrr you need
- moldex 6604 sparkplugs
- moldex 6654 sparkplugs corded
- moldex 6615 sparkplugs metal detectable
- moldex 6684 sparkplugs jar
- moldex 6800 pura fit
- moldex 6900 pura fit corded
- moldex 6600 softies
- moldex 6650 softies corded
Frequently Asked Questions
Is the foam in the 6684 jar acoustically different from the boxed 6604 or corded 6654?
No. The 6684 jar holds the identical firm dual-layer SparkPlugs foam rated NRR 33 (ANSI S3.19) as the boxed Moldex 6604 and the corded 6654. The only difference is packaging — loose plugs in an open jar versus a box of wrapped pairs. Choose the jar for deployment convenience, not for any acoustic advantage.
What is the real-world protection from NRR 33 SparkPlugs after derating?
NRR 33 is a laboratory value. NIOSH recommends derating foam plugs by 25%, which trims roughly 8 dB off the label; OSHA's enforcement formula ((NRR-7)/2) yields about 13 dB of estimated protection. So plan around 13 to 25 dB of real-world reduction, not 33. Our NRR explained guide and how to calculate the NRR you need walk through the math for your specific exposure.
When is the 6684 jar the right choice versus a boxed or corded SparkPlug?
Pick the jar when you need accessible, low-cost-per-pair hearing protection sitting at a fixed secondary workstation, bench, or tool cart with no dispenser to mount. Pick the boxed 6604 when you need individually wrapped pairs workers can pocket, and the corded 6654 when a cord-mandate or drop-loss risk applies.
Is an open jar hygienic enough for industrial use?
For most general-industry and construction settings, yes — provided the lid stays closed between uses and workers never return used or handled plugs to the jar. It is not suitable for food, pharmaceutical, clean-room, or sterile environments, and you should retire a jar showing oil, dust, or moisture inside rather than risk inserting contaminated foam.
Can I use the 6684 jar in a food-processing plant?
No. The jar's loose, unwrapped plugs offer no HACCP traceability, and SparkPlugs are not metal-detectable. For food, beverage, or pharma lines with X-ray or metal-detection controls, use a metal-detectable plug like the 6615 instead. Browse the full hearing protection collection for compliant options.
How do I insert these firm SparkPlugs correctly from the jar?
Roll the firm outer skin tightly between thumb and forefinger, reach over your head and pull the ear up and back to straighten the canal, insert deeply while the foam is still compressed, then hold for 30 to 60 seconds while it expands. A poor roll-down is the most common reason plugs underperform their NRR. See our step-by-step how to insert foam earplugs guide.
Are SparkPlugs too firm for some workers compared to other foam plugs?
SparkPlugs use a firmer foam than Moldex's softest plugs, which gives a confident deep seal in larger canals but can feel pressured in small or sensitive ears. Workers who find them uncomfortable usually do better with the softer 6800 Pura-Fit or the low-pressure 6600 Softies, both also NRR 33.
How does the 6684 compare to the 6800 Pura-Fit for the same NRR 33?
Both block to NRR 33, so on paper they protect the same. The difference is feel: SparkPlugs are firmer and seat deep for a secure seal, while the Pura-Fit is softer and tapered for all-shift comfort and easier fit in smaller canals. Choose SparkPlugs for grip and deep seating, Pura-Fit for comfort-driven compliance.
Should I choose the uncorded jar or a corded SparkPlug for my crew?
Uncorded jar plugs suit fixed-station workers who insert once and stay put, keeping cords out of the way. A corded plug like the 6654 is better where workers remove plugs frequently, move between areas, or where dropped-object and loss risk matters. Both deliver identical NRR 33 attenuation.
Will these reusable jar plugs hold up to multiple insertions?
SparkPlugs are single-use disposable foam, not washable reusable plugs — replace them once soiled, oily, or no longer expanding fully. If you want washable, multi-use protection, look at flanged options in the reusable earplugs collection rather than any foam SparkPlug.
Does the bulk jar actually save money versus buying boxes?
Generally yes. Loose unwrapped plugs in a bulk jar avoid individual-wrapper cost and ship more units per container, lowering per-pair price at high-turnover stations. The trade-off is no metering and no wrapper protection, so the savings make sense only where open-access dispensing is acceptable. Compare current pricing on the product page.
Is NRR 33 the highest protection I can get, or should I go higher?
NRR 33 is at the top of the foam earplug range — you will not find meaningfully higher single-plug numbers. If your derated exposure still exceeds the 90 dBA PEL, the answer is dual protection (plugs plus muffs), not a higher-NRR plug. See highest NRR ear plugs and ear plugs vs ear muffs to plan combined protection.
Do open-jar earplugs satisfy OSHA hearing-conservation requirements?
Yes. OSHA 29 CFR 1910.95 requires that hearing protectors be available at no cost to employees exposed at or above the 85 dBA action level and that workers be trained to use them — it does not mandate individual wrapping. A jar placed at the workstation meets the availability requirement, provided training on correct insertion is also delivered.
Should workers be fit-tested on SparkPlugs even with an NRR 33 rating?
Fit testing (field attenuation estimation per ANSI/ASA S12.6) is the only way to confirm an individual actually achieves the protection the label implies, since real-world results vary widely by fit. The firm SparkPlug seats well in many canals but may pressure smaller ones, so fit verification is worthwhile — especially before relying on the plug as a worker's sole protection.
Where does the 6684 jar fit in a hearing-conservation program of foam and reusable plugs?
Use it as a point-of-use stock at fixed secondary stations, paired with wrapped or corded SparkPlugs for mobile workers and a softer or reusable plug for workers who can't tolerate firm foam. Explore the broader range in the foam ear plugs and NRR 33 ear plugs collections, and review top picks in our best foam ear plugs guide.
Why trust WC Safety
Industrial PPE specialists. We do not accept manufacturer payment for placement.
Industrial PPE specialists. We do not accept manufacturer payment for placement.
Reviewed by
Steven Eaton, WC Safety Editorial — guidance reflects current OSHA, NIOSH and ANSI practice.
Steven Eaton, WC Safety Editorial — guidance reflects current OSHA, NIOSH and ANSI practice.
Our standards
Ratings combine published specs, hands-on familiarity, and verified customer data where available; we do not fabricate lab tests.
Ratings combine published specs, hands-on familiarity, and verified customer data where available; we do not fabricate lab tests.
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