NRR 33, Multicolor, Latex-Free: Is the Moldex 6684 the Best Disposable Earplug for Industrial Compliance?

Moldex 6684 SparkPlugs Uncorded Earplug Jar NRR 33 — 50 Pairs Review (2026)

When your hearing conservation program requires documented compliance monitoring across dozens of workers, the earplug you choose has to do more than block sound. It has to be visible, comfortable enough that workers actually keep it in, and certified to the attenuation standard your safety plan depends on. The Moldex 6684 SparkPlugs targets exactly that intersection: an NRR 33 disposable foam earplug in vivid multicolor that supervisors can spot at a glance — sold in a 50-pair dispenser jar for high-volume industrial use.

We reviewed this earplug against ANSI S3.19-1974 (the test standard used by its NRR rating) and OSHA 29 CFR 1910.95 requirements for hearing protection adequacy. The Moldex 6684 is certified latex-free, PVC-free, and chloroprene-free — an important detail for facilities with chemical-contact or allergen policies. At an NRR of 33, it sits at the top of the single-use foam category, suitable for noise environments up to roughly 103 dBA TWA when applying the OSHA 50% derating method (yielding approximately 13 dB of effective real-world attenuation).

The 50-pair jar format is the workhorse purchase for safety coordinators running a dispenser program. Each pair is individually identifiable by color — neon green, blue, pink, yellow — which also helps workers distinguish their own pair in multi-earplug environments. If you are stocking a hearing protection station or building out a OSHA Hearing Conservation Program, this jar format simplifies replenishment and keeps cost per pair low.

Who Should Buy the Moldex 6684 SparkPlugs?

The 6684 is the right buy for safety managers and procurement coordinators running a dispenser-based hearing program in general manufacturing, construction, assembly, or logistics environments. The jar format fills standard 50-pair wall dispensers without additional packaging. The high-visibility color coding supports walk-through compliance checks — supervisors can confirm proper insertion from a distance without stopping production.

Individual workers benefit from the NRR 33 rating in the loudest zones: stamping presses, grinders, pneumatic tools, and HVAC equipment. For anyone researching the broader category, our Best Earplugs for Work guide and Best Moldex Earplugs roundup both include the 6684 in their top picks. If allergen documentation matters for your facility PPE policy, the triple-free certification (latex, PVC, chloroprene) makes this one of the cleanest material profiles in the disposable foam segment.

What the Moldex 6684 Does Well

Maximum-Category NRR Attenuation

An NRR of 33 dB is the practical ceiling for disposable foam earplugs tested under ANSI S3.19-1974. Under the OSHA 29 CFR 1910.95 derating method — which halves the labeled NRR and subtracts 7 — the 6684 delivers approximately 13.5 dB of real-world attenuation in a mixed workforce. For the louder NIOSH A-weighting method, effective attenuation is approximately 22 dB. Either way, NRR 33 gives safety coordinators the widest buffer for TWA exceedances up to 103 dBA. See our NRR Hearing Protection Guide for a full breakdown of which derating method applies to your program.

Compliance Visibility at Scale

The multicolor foam — rotating through neon green, blue, pink, and yellow — is a deliberate Moldex engineering decision, not an aesthetic one. In a loud environment where verbal instruction is impractical, a supervisor doing a walk-through can confirm proper deep-insertion by the small foam flange sitting flush at the ear canal. Contrast that with skin-tone or beige foam that blends into the ear at a distance. For facilities under OSHA mandatory Hearing Conservation Program requirements, visual compliance monitoring is a documented requirement — this earplug makes that job faster.

Material Certifications for Sensitive Environments

Latex allergies affect a meaningful segment of the general workforce. The 6684 latex-free, PVC-free, and chloroprene-free formulation eliminates the three most common earplug-related contact sensitizers. PVC-free is particularly relevant for facilities with chemical-exposure policies or workers who develop irritation from prolonged foam contact. This puts the 6684 alongside the cleanest material profiles in the ear plugs category.

Jar Dispenser Format

The 50-pair jar format is purpose-built for PPE dispenser stations. It eliminates blister-pack waste, reduces per-pair handling time during replenishment, and pairs directly with standard 50-pair wall-mount earplug dispensers. For high-volume programs burning through 200+ pairs per week, the jar is the operationally correct format — loose pairs in a bin invite contamination and tracking problems.

Verified Buyer Satisfaction

With a 4.8/5 rating across more than 1,400 verified purchasers, the 6684 has a demonstrated track record of fit satisfaction across diverse ear canal anatomies. Common positive themes center on comfort during extended shifts, the vibrant color making them easy to find in a kit bag, and reliable expansion after roll-down compression. Comfort compliance matters: an NRR 33 earplug worn intermittently provides far less effective protection than an NRR 25 worn consistently.

Where the Moldex 6684 Falls Short

Roll-Down Insertion in Field Conditions

All foam earplugs rated NRR 33 require proper roll-down compression insertion to achieve rated attenuation. The 6684 is no exception. In practice, workers with sweaty or gloved hands may struggle to achieve a tight enough roll for full expansion. OSHA 29 CFR 1910.95 Appendix B explicitly notes that improper insertion is the primary cause of real-world attenuation loss. Safety coordinators should budget for insertion training during onboarding — a 10-minute demo closing the gap between rated and real-world NRR is worth more than a premium earplug inserted incorrectly.

Not Metal-Detectable

The standard 6684 foam formulation is not metal-detectable. Food processing, pharmaceutical manufacturing, and any regulated facility using metal-detection lines must use the Moldex 6615 corded variant, which includes metal-detectable foam. Purchasing the 6684 for a food-safe environment would create a contamination-documentation gap.

Uncorded Means Higher Loss Rate

Uncorded earplugs disappear. Workers moving between loud and quiet zones frequently remove them, set them down, and lose them. The corded alternative keeps the pair together and around the neck during brief noise-free intervals. If your loss rate is driving up program cost, weigh the per-pair price premium of the corded SKU against replenishment frequency. Our Reusable vs Disposable Earplugs guide covers the full lifecycle cost comparison.

Single-Use Design

The 6684 is a single-use disposable. If your program is evaluating the environmental footprint of hearing protection or workers want to reuse protection across a full shift, a reusable banded or pod-style earplug may be a better fit. The 6684 is designed for clean-insertion-and-replace use, not extended reuse cycles.

Competitor Comparison

Compatible Dispensers, Storage & PPE Combinations

The 6684 jar is sized for standard 50-pair earplug wall dispensers. Mount dispensers at hearing protection zone entry points per OSHA 29 CFR 1910.95(i)(3), which requires hearing protection to be available without cost to employees in designated noise zones.

For full-entry PPE station setups, pair the 6684 dispenser with appropriate PPE bundles:

• Safety glasses: Over-the-ear safety glasses (wrap-around temples) are fully compatible with in-ear earplugs — no interference with the earplug body. The 6684 uncorded format is particularly convenient in glasses-plus-earplug environments versus earmuffs.
• Hard hats: In-ear earplugs do not create the helmet-seal interference that earmuffs do. Workers in hard-hat environments benefit from using high-NRR in-ear protection like the 6684 instead of earmuff combinations that may gap at the hard hat brim.
• Dust masks and respirators: The uncorded format eliminates the cord-plus-respirator-straps tangle common in multi-PPE environments. Explore our full hearing protection collection for station-ready bundles.

NRR, OSHA 29 CFR 1910.95, and ANSI S3.19 — What the Numbers Mean

The Noise Reduction Rating (NRR) is the federally required attenuation label under EPA 40 CFR Part 211, derived from ANSI S3.19-1974 laboratory testing. It is not a field performance guarantee — it is a controlled-condition maximum used to calculate program-level adequacy.

Under OSHA 29 CFR 1910.95, employers must ensure that hearing protection reduces employee noise exposure to at least 90 dBA TWA (85 dBA for workers already showing audiogram standard threshold shift). The OSHA-recommended derating method: (NRR - 7) divided by 2. For the 6684 at NRR 33: (33 - 7) divided by 2 = 13 dB effective attenuation. That means the 6684 is OSHA-adequate for TWAs up to approximately 103 dBA.

NIOSH recommends a more conservative derating: 75% for formable foam earplugs, yielding approximately 33 x 0.75 = 24.75 dB attenuation. Under NIOSH, the 6684 is adequate through approximately 115 dBA TWA. For a complete guide on choosing between OSHA and NIOSH methods for your program, see our NRR Hearing Protection Guide. For a broader program framework, our OSHA Hearing Conservation Program Guide covers audiometric testing, training, and recordkeeping requirements alongside your earplug selection.

When evaluating whether to use earplugs, earmuffs, or a combination, our Best Hearing Protection for Industrial Workers guide and Best Earmuffs for Hearing Protection roundup cover the tradeoffs at each noise level. For the corded vs uncorded decision specifically, see Reusable vs Disposable Earplugs.

Total Cost of Ownership

At approximately $19.99 per 50-pair jar, the 6684 runs roughly $0.40 per pair. For a 100-worker facility consuming one pair per worker per day, that is $40 per day or approximately $10,000 per year in earplug costs alone — before accounting for dispenser hardware, program administration, and audiometric testing.

Cost reduction levers:

• Buy the 200-pair box (6680): Reduces per-pair cost meaningfully at scale.
• Insertion training reduces waste: Workers who insert correctly the first time do not throw away pairs after failed insertions.
• Dispenser placement reduces loss: Point-of-use dispensers reduce replacement costs versus individual distribution.
• Compare vs reusable: Banded or reusable pod earplugs have higher up-front cost but lower per-use cost over 30-60 uses per pair. Our Reusable vs Disposable guide models this tradeoff.

Final Verdict

The Moldex 6684 SparkPlugs earns its 4.7/5 rating by delivering on the three requirements that matter most to industrial safety programs: maximum-category NRR 33 attenuation, ANSI S3.19-certified performance, and a compliance-visible design that supervisors can actually verify in the field. The allergen-free material set (latex-free, PVC-free, chloroprene-free) removes the most common chemical contact barriers, and the 50-pair jar format is the right match for dispenser-station programs.

The limitations are real but narrow: roll-down insertion still requires training and clean hands, the uncorded design means higher loss rates in some environments, and metal-detection requirements mandate a different SKU. Within those constraints, the 6684 is a top-tier disposable earplug for general manufacturing, construction, and assembly environments. If you are building or refreshing your hearing conservation program, start here and size the jar or box format to your replenishment cycle.

Frequently Asked Questions

What is the NRR of the Moldex 6684?

The Moldex 6684 has an NRR (Noise Reduction Rating) of 33 dB, tested under ANSI S3.19-1974. This is the highest rating available for single-use disposable foam earplugs.

Is the Moldex 6684 OSHA-compliant?

Yes. Under OSHA 29 CFR 1910.95 and the OSHA derating formula — (NRR - 7) divided by 2 — the 6684 delivers approximately 13 dB of real-world attenuation, making it OSHA-adequate for noise environments up to approximately 103 dBA TWA.

How do I properly insert the Moldex 6684?

Roll the earplug tightly between your fingers until it is compressed to a thin cylinder. Reach over your head with the opposite hand, pull the top of your ear up and back to straighten the ear canal, then insert the compressed earplug. Hold it in place for 20-30 seconds while it expands to fill the canal. Proper insertion is required to achieve rated attenuation — partial insertion significantly reduces protection.

Are the Moldex 6684 SparkPlugs latex-free?

Yes. The 6684 is certified latex-free, PVC-free, and chloroprene-free. This triple-free material profile makes it suitable for workers with latex sensitivity or facilities with allergen-control policies.

Can I reuse the Moldex 6684?

No. The 6684 is a single-use disposable earplug. Reusing foam earplugs compresses the cell structure and reduces rated attenuation. Replace each pair after a single shift. For reusable alternatives, see our Reusable vs Disposable Earplugs guide.

What is the difference between corded and uncorded earplugs?

Corded earplugs are joined by a cord that keeps the pair together when removed. Uncorded earplugs like the 6684 are individual — workers tend to lose them at higher rates in environments with frequent insert-remove cycles. See our Reusable vs Disposable guide for a full comparison.

Are Moldex SparkPlugs suitable for food processing facilities?

The standard 6684 is not metal-detectable and should not be used in food processing or pharmaceutical facilities with metal-detection lines. Use the Moldex 6615 SparkPlugs corded variant, which includes metal-detectable foam formulation.

How many pairs are in the Moldex 6684 jar?

The Moldex 6684 jar contains 50 pairs (100 individual earplugs). The jar format is designed to fit standard 50-pair wall-mount earplug dispensers used in industrial hearing protection stations.

What colors do Moldex 6684 SparkPlugs come in?

The SparkPlugs come in rotating vivid multicolors including neon green, blue, pink, and yellow. The colors are not user-selectable — the jar contains mixed colors by design, supporting visual compliance monitoring across workers.

What noise level is the Moldex 6684 adequate for under OSHA?

Using the OSHA derating method — (33 - 7) divided by 2 = 13 dB — the 6684 is adequate for noise exposures up to approximately 103 dBA TWA. For environments above 103 dBA, dual protection (earplugs plus earmuffs) is required under OSHA 29 CFR 1910.95.

What ANSI standard does the NRR 33 rating follow?

The NRR 33 rating is derived from ANSI S3.19-1974 laboratory testing, which is the EPA-required standard for all hearing protector labeling in the United States.

Do the Moldex 6684 earplugs fit small ear canals?

The 6684 uses a medium-to-standard diameter foam. Workers with small ear canals may find the foam diameter oversized. The 4.8/5 rating across 1,400+ buyers suggests broad fit compatibility, but individual fit testing is always recommended for hearing conservation program accuracy.

How does the SparkPlugs NRR compare to other Moldex earplugs?

The SparkPlugs NRR 33 is at the top of the Moldex earplug lineup. Other Moldex foam earplugs such as the Pura-Fit and Meteors share the NRR 33 tier. The primary differentiation is in shape, diameter, and material. See our Best Moldex Earplugs guide for a full series comparison.

What is the best earplug for industrial work?

For most industrial environments requiring NRR 33 protection in a disposable format, the Moldex 6684 is one of the top choices due to its material certifications, compliance-visible design, and dispenser-ready jar format. Our Best Earplugs for Work guide covers the full comparison including banded, reusable, and corded alternatives.

Can earplugs be combined with earmuffs for higher protection?

Yes. Dual protection — earplugs plus earmuffs — is required by OSHA when a single protector is not adequate for the noise level. OSHA adds 5 dB to the higher-rated protector derated value for dual protection. For environments above 103 dBA, dual protection with the 6684 as the earplug component provides adequate coverage through approximately 108+ dBA. See our Best Earmuffs guide for compatible over-ear options.

Are Moldex SparkPlugs good for sleeping or traveling?

The 6684 is rated and sold as an industrial occupational safety earplug, not a consumer sleep or travel product. While the NRR 33 rating would provide significant noise reduction for sleep, the product is not marketed for that application. A consumer-oriented earplug with a lower NRR and softer foam formulation is typically more comfortable for extended wear outside of industrial settings.

Where can I buy the Moldex 6684 in bulk?

The 6684 50-pair jar is available at WC Safety for direct purchase. For larger volume programs, the Moldex 6680 200-pair box offers a lower per-pair cost. Both SKUs are also available via Amazon (wcsafety04-20).

Written by Steven Eaton — Safety Equipment Specialist, WC Safety Editorial
Published: June 12, 2026 | Category: Ear Plugs | Brand: Moldex | Series: SparkPlugs

Review Methodology

This review is based on: published product specifications from Moldex and the WC Safety product page; regulatory standards including OSHA 29 CFR 1910.95 and ANSI S3.19-1974; EPA labeling requirements under 40 CFR Part 211; and verified buyer ratings from Amazon (4.8/5, 1,437 ratings as of June 2026). No laboratory attenuation testing was conducted independently by WC Safety. NRR figures are reproduced from manufacturer labeling as required under federal law. Derating calculations follow OSHA Appendix B to 1910.95 methodology.