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Industrial Safety Equipment & PPE — ANSI/OSHA Compliant
Industrial Safety Equipment & PPE — ANSI/OSHA Compliant
May 13, 2026 Updated July 25, 2026 Steven Eaton

Moldex 6645 SparkPlugs PlugStation Review: 500-Pair Earplug Dispenser (NRR 33)

WC Safety Editorial Verdict: 4.5/5

WC Safety Editorial Verdict — 4.5/5. The Moldex 6645 SparkPlugs PlugStation is the right call when one secondary station feeds enough workers that a 250-pair 6605 needs refilling too often: you get the same washable multi-flange NRR 33 SparkPlugs in a higher-capacity, single-dispense cabinet that keeps refill logs clean for hearing protection compliance. We dock half a point only because the multi-flange profile suits a narrower range of ear canals than a roll-down foam plug, so high-throughput stations should pair it with a fitting reminder and a foam fallback.

Best understood as a stocking and accountability tool rather than a different earplug — if you don't need 500 pairs at one point, the Moldex 6604 SparkPlugs box or the Moldex 6684 SparkPlugs jar deliver the same protection for less.

Moldex 6645 SparkPlugs PlugStation Review: Optimizing Volume-Per-Month at High-Throughput Secondary Earplug Stations

When a facility runs three shifts and operates multiple secondary dispensing points — tool rooms, guardhouses, visitor entry, break room exits — the question is not just which earplug to specify but how to keep those stations stocked without weekly refill runs. The Moldex 6645 Check Price on Amazon → PlugStation is built for that scenario: a higher-capacity SparkPlugs dispenser that reduces refill frequency at your busiest secondary stations while maintaining the individual dispensing accountability that makes PlugStation systems valuable for OSHA compliance documentation.

OSHA 29 CFR 1910.95: At 85 dB TWA, hearing protectors must be available. At 90 dB TWA, they must be worn. Documenting dispenser placement and refill logs at each hazard-zone entry point supports compliance demonstration during inspections.

What Makes the 6645 Different from the 6605?

The Moldex 6605 PlugStation holds 250 pairs of uncorded SparkPlugs — appropriate for light-traffic secondary stations. The 6645 is the higher-capacity variant in the SparkPlugs PlugStation family, designed for stations that burn through earplug inventory faster. Where the 6605 might need weekly refills in a moderate-traffic environment, the 6645's larger capacity can extend that interval significantly, reducing the labor cost of safety supply management.

The earplug itself is identical: SparkPlugs multi-flange design, NRR 33, bright yellow-green thermoplastic elastomer, no roll-down required. The difference is in how long the dispenser can operate between refill events — a meaningful operational factor in large facilities where the safety manager cannot run refill rounds daily.

SparkPlugs Specifications

Specification Detail
SKU 6645
Earplug model SparkPlugs
NRR 33 dB
Real-world attenuation (NRR÷2) ~16.5 dB
Style Multi-flange triple-flange
Color Bright yellow-green
Corded No (uncorded)
Dispenser type PlugStation (individual pairs)
Wall-mount bracket Included
NIOSH listed Yes

Volume-Per-Month Planning for Multi-Shift Facilities

The key question for any safety supply manager running PlugStation dispensers is: how do I right-size dispenser capacity to my daily draw rate?

Consider a facility with:

  • 3 shifts, 5 days/week
  • A secondary station (visitor entry + contractor check-in) drawing an average of 15 pairs per day
  • A tool crib window drawing 25 pairs per day
Station Daily Draw 6605 (250-pair) Refill Interval 6645 Refill Interval
Visitor entry 15 pairs/day ~16 days Extended interval
Tool crib 25 pairs/day ~10 days Significantly extended
Combined (2 stations) 40 pairs/day ~6 days Longer cycle

Reducing refill frequency from weekly to bi-weekly or monthly at secondary stations reduces the total labor hours spent on safety supply management — a real operational cost in multi-site or large-footprint facilities.

Multi-Flange vs. Foam: Why SparkPlugs Work at High-Volume Stations

At a high-throughput secondary station, the earplug format matters as much as the dispenser capacity. SparkPlugs require no roll-down — workers pull a pair and insert directly. This speed advantage is significant when contractors and visitors are queued at a guardhouse entry: a foam earplug requires 20–30 seconds of roll-down and hold time; a SparkPlugs takes 5–10 seconds to insert correctly.

The tradeoff versus foam earplugs deserves acknowledgment:

  • SparkPlugs advantages at high-traffic secondary stations: Faster insertion, no contaminated-hands roll-down concern, consistent seal geometry.
  • Foam plug advantages (Pura-Fit, Mellows): Workers who find multi-flange uncomfortable often show higher compliance with foam. See the Moldex 6844 Pura-Fit PlugStation and the Moldex 6846 Mellows PlugStation for foam-format PlugStation options.

OSHA NRR Compliance: SparkPlugs at 33 dB

Environment Ambient dB Effective Exposure (NRR÷2) Status
Typical machining 94 dB 77.5 dB Compliant
Assembly with impact tools 98 dB 81.5 dB Compliant
Metal stamping 103 dB 86.5 dB Monitor closely
Chipping hammer 108 dB 91.5 dB Add earmuffs

NIOSH's derating methodology (NRR÷2) is recommended over the OSHA method (subtract 7, then divide by 2) because it better reflects real-world insertion quality variance. Read more at our NIOSH standards guide.

Ideal Use Cases for the 6645 PlugStation

  • Large manufacturing plants with 3-shift operations — volume draws that would require twice-weekly 6605 refills are handled by the 6645's higher capacity on a longer cycle.
  • Facilities with distributed secondary stations — when multiple dispensers are mounted across a large floor plan, reducing per-station refill frequency saves meaningful technician time.
  • Contractor-heavy sites during construction phases — unpredictable daily contractor headcount creates demand spikes; the 6645's buffer capacity handles those spikes without running empty.
  • Facilities with limited safety staff — fewer refill events per month means the safety coordinator can focus on other compliance tasks.

How to Refill the Moldex 6645 PlugStation

  1. Press the dual release tabs on the front panel and swing the door open.
  2. Remove any residual pairs from the magazine channel.
  3. Load SparkPlugs refill pairs into the channel vertically, foil side facing the dispense port.
  4. Do not force pairs — they should stack freely under gravity.
  5. Close the front panel until both tabs click securely.
  6. Pull one pair to confirm smooth dispensing operation.
  7. Log the refill date and pair count in your hearing conservation program records.

Document refill events. OSHA inspectors may request proof that dispensers were maintained and available throughout the compliance period.

PlugStation vs. EcoStation vs. Bulk Box

Feature 6645 PlugStation EcoStation (6704) Bulk Box
Dispense method Individual pairs Bulk hopper Open box
Hygiene High Medium Low
Refill frequency (high-volume) Extended interval Longer interval N/A
Per-plug accountability High Low None
Cost per pair Higher Lower Lowest
Best for High-throughput secondary stations High-volume primary lines Storeroom stock

For very high-volume primary-line dispensing where individual wrap is less important, see the Moldex 6704 SparkPlugs EcoStation refill. For other EcoStation formats, see the Moldex 6708 Meteors EcoStation and Moldex 6706 Pura-Fit EcoStation.

Other SparkPlugs PlugStation Options:
Moldex 6605 (250-pair uncorded) | Moldex 6644 (corded SparkPlugs) | Moldex 6646 Goin' Green PlugStation | Moldex 6875 Meteors PlugStation

Frequently Asked Questions

What is the NRR of SparkPlugs in the 6645 PlugStation?
NRR 33 dB, with a real-world attenuation of approximately 16.5 dB when applying the NIOSH NRR÷2 derating formula. This is sufficient for most industrial environments under 105 dB.
How does the 6645 differ from the 6605 PlugStation?
Both dispense uncorded SparkPlugs earplugs, but the 6645 has a higher capacity than the 6605 (250-pair). The 6645 is the better choice for high-throughput secondary stations where the 6605 would require frequent refilling.
How long will a 6645 PlugStation last at a busy station?
It depends on daily draw rate. At 25 pairs per day, a 6605 lasts about 10 days. The 6645's higher capacity proportionally extends that interval. Track your station's daily draw for the first month to establish a reliable refill schedule.
Does the SparkPlugs multi-flange design work for all workers?
Most workers adapt quickly to multi-flange insertion. Workers with very narrow ear canals may find foam earplugs more comfortable. If compliance is an issue with SparkPlugs, consider the Moldex 6844 Pura-Fit PlugStation or Moldex 6847 Mellows PlugStation as alternatives.
Can I use any SparkPlugs refill pairs in the 6645?
Yes, standard SparkPlugs uncorded refill pairs are compatible with the 6645 PlugStation. Corded SparkPlugs pairs are not — those are for the 6644 dispenser.
Is the 6645 PlugStation tamper-resistant?
Yes. The front panel requires simultaneous depression of two release tabs to open, which prevents accidental opening and deters casual tampering. The dispense mechanism only releases one pair at a time.
What OSHA documentation supports PlugStation use?
OSHA 29 CFR 1910.95(i) requires that hearing protectors be available at no cost to exposed workers. Maintaining a log of dispenser installation dates, refill dates, and locations satisfies documentation requirements during inspections.
Are SparkPlugs suitable for contractors and visitors, not just employees?
Yes. OSHA 1910.95 requires protection for all personnel in hearing-hazard zones, including contractors and temporary workers. The PlugStation's individual dispensing format is ideal for visitor and contractor entry points where a brief instruction and one pair per person is the protocol.
What is the real-world insertion quality concern with SparkPlugs at secondary stations?
Multi-flange earplugs create a consistent seal with less technique dependence than foam, but workers still need basic insertion training. Post a laminated insertion instruction card near each PlugStation. Moldex provides insertion guides on their website.
Is the 6645 PlugStation refillable with Goin' Green or Mellows pairs?
No. PlugStation dispensers are model-specific. The 6645 is designed for SparkPlugs refill pairs. For Goin' Green dispensing, see the Moldex 6646 PlugStation or 6647 PlugStation.
Can multiple 6645 PlugStations be mounted in one area?
Yes. High-traffic entry points — such as a large plant entrance used by dozens of workers per shift — benefit from two dispensers mounted side by side to prevent queuing. Each dispenser operates independently.
Do SparkPlugs work under hard hats?
Yes. SparkPlugs insert entirely into the ear canal with no external cup or band, making them fully compatible with hard hats, safety glasses, and respirators. This is a significant advantage over earmuffs in multi-PPE environments.
How should I train workers to use SparkPlugs correctly?
Pull the outer ear up and back to straighten the ear canal, then insert the SparkPlugs stem until the outermost flange seats at the canal entrance. A proper seal will feel slightly pressurized and sounds will be noticeably muffled. The insertion takes 5–10 seconds with practice.
What is the estimated annual pair consumption for a 100-person facility?
At one pair per worker per day, five days per week: 100 × 5 × 52 = 26,000 pairs annually. Adjust for shift overlap, contractor volume, and secondary-station draw rates. This calculation justifies the PlugStation volume purchasing economics.
Where can I buy the Moldex 6645 PlugStation?
Browse the WC Safety earplug collection or check availability on Amazon Check Price on Amazon →. For related hearing protection options, see the full hearing protection collection.

Also see: safety gloves, hard hats, best in-ear hearing protection for shooting.

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.

Pros & Cons

Pros
  • Houses 500 pairs of NRR 33 SparkPlugs in one cabinet, cutting refill rounds at high-traffic stations versus the 250-pair 6605
  • Single-pair dispensing supports clean per-station refill logs for OSHA 1910.95 documentation
  • Washable, reusable multi-flange TPE plugs mean no roll-down step and no dirty-hands insertion at the station
  • NRR 33 is at the top of the earplug range, giving derating headroom in 95-105 dBA zones
  • Uncorded format keeps the dispenser tidy and avoids cord tangles at walk-up points
  • Refillable with standard 6604/6654-family SparkPlugs pairs, so consumable cost stays low
Cons
  • Multi-flange sizing fits a narrower range of ear canals than roll-down foam, so some workers seal poorly
  • 500-pair capacity is wasted spend at low-traffic stations where a 6605 or a jar suffices
  • Uncorded plugs are easy to lose between insertions versus the corded 6654 for in-and-out tasks
  • Dispenser hardware adds cost over simply stocking a bulk box of the same plug

Who It's For

Buy it if:

  • Safety managers stocking a single high-throughput entry point (turnstile, tool crib, plant gate) that burns through a 250-pair dispenser too fast
  • Multi-shift facilities that need per-station refill records for 1910.95 audit trails
  • Operations wanting a no-roll-down, washable reusable plug at walk-up stations to reduce insertion contamination
  • Plants in 95-105 dBA zones that want NRR 33 derating headroom at the dispense point

Look elsewhere if:

  • Low-traffic stations or small crews, where a 6605, a 6684 jar, or a bulk box is the better value
  • Workers who seal poorly on multi-flange plugs and need a roll-down foam option
  • Tasks needing earplugs tethered for frequent removal, which call for the corded 6654 instead
  • Buyers who only need loose plugs and don't need a wall-mounted single-dispense cabinet

Related Resources

Frequently Asked Questions

Does the NRR 33 on the 6645 SparkPlugs mean I actually get 33 dB of protection?

No. The NRR 33 printed on SparkPlugs is a laboratory rating under ANSI S3.19; real-world attenuation is lower. NIOSH recommends derating foam-style plugs by about 25%, and OSHA's estimate for mixed real-world use is (NRR-7)/2, which puts NRR 33 near 13 dB of effective protection. Always size protection to your measured exposure rather than the label. See what is NRR noise reduction rating explained.

How do I know NRR 33 from the PlugStation is enough for my noise level?

Subtract your derated protection from the measured TWA. For a 100 dBA exposure, applying OSHA's (33-7)/2 method gives roughly 13 dB of real protection, leaving about 87 dBA at the ear — under the 90 dBA PEL but still above the 85 dBA action level. Run the numbers for your zone using how to calculate the NRR you need.

Are the SparkPlugs in the 6645 reusable, or single-use like foam?

They are reusable. SparkPlugs are a washable thermoplastic-elastomer multi-flange plug, not a disposable foam plug. Workers can rinse and re-wear a pair across a shift, which is part of why a 500-pair dispenser lasts so long. If you prefer single-use foam economics instead, compare the options in disposable ear plugs.

How is the multi-flange SparkPlug different from a roll-down foam plug at the station?

A roll-down foam plug is compressed, inserted, and expands to seal, which adapts to more ear-canal shapes. The SparkPlug's pre-formed flanges push straight in with no roll-down — faster and cleaner at a walk-up dispenser, but the fixed profile seals fewer canal sizes. For workers it doesn't fit, keep a foam fallback from foam ear plugs.

Is NRR 33 from SparkPlugs the highest protection I can get from an earplug?

NRR 33 sits at the top of the earplug range; very few plugs exceed it, and most reusable flanged plugs rate lower. If maximum single-device attenuation is the goal, the SparkPlug is a strong pick — see how it stacks up against other top performers in highest NRR ear plugs.

Should I choose the uncorded 6645 or a corded SparkPlug for the same station?

Choose uncorded when workers stay in the noise zone for the shift and a cord would tangle at the dispenser. Choose corded when they move in and out frequently and need plugs tethered around the neck between uses. The corded equivalent is reviewed in Moldex 6654 SparkPlugs corded.

Is the 6645 dispenser worth the cost versus just stocking a bulk box of SparkPlugs?

The dispenser adds hardware cost over loose plugs, but it buys single-pair dispensing, contamination control, and a clean refill log for compliance. At a high-traffic station that accountability is usually worth it; at a quiet station it isn't, and a box or the Moldex 6684 SparkPlugs jar is the better value.

When should I stock the 6645 instead of a smaller SparkPlugs dispenser?

Stock the 6645's larger capacity only where throughput is high enough that a smaller 250-pair dispenser would need frequent refills — a plant gate, tool crib, or shared turnstile. For a moderate or light-traffic point, the smaller dispenser ties up less inventory and is the more economical choice.

Do SparkPlugs from the 6645 stay comfortable across a full shift?

The TPE flanges sit lightly in the canal and many workers tolerate them well for long wear, but flanged plugs apply more localized contact than expanded foam, so fit-sensitive workers may prefer foam over an 8-12 hour shift. Offer a foam alternative for those workers; see the picks in best foam ear plugs.

Can the 6645 cover OSHA hearing-conservation needs by itself, or do I need backup protection?

As a dispense point it covers earplug supply at one station, but a compliant program offers a choice of protectors and a fallback. Keep a second style or muffs available so every worker can get an adequate seal. The 1910.95 program is built on availability at 85 dBA and mandatory use at 90 dBA across your hearing protection options.

How do SparkPlugs from the 6645 compare to a reusable flanged plug like Pura-Fit's foam alternative?

SparkPlugs are a reusable multi-flange plug, while Pura-Fit is a roll-down foam plug — different insertion and fit behavior at the same NRR class. A station may want both: flanged for clean walk-up use, foam for canals the flanges don't seal. The foam sibling is reviewed in Moldex 6800 Pura-Fit.

Would earplugs from this dispenser be enough, or should some workers use muffs?

Plugs alone usually suffice up to the low-to-mid 100s dBA once derated, but intermittent wearers, workers who can't seal a plug, or very high exposures are better served by muffs — or dual protection. Decide per task using ear plugs vs ear muffs.

Are the SparkPlugs in the 6645 the same plug sold in the 6604 box, just dispensed differently?

Yes — the plug itself is the standard uncorded SparkPlug; the 6645 only changes the stocking format to a high-capacity single-dispense cabinet. If you don't need the cabinet, the loose-pack version reviewed as the Moldex 6604 SparkPlugs delivers identical protection for less.

Why pick an NRR 33 plug for the dispenser instead of a lower-rated one?

Specifying NRR 33 at the station gives you derating headroom so the same dispenser covers louder zones without overprotecting quiet ones — a worker can simply not fully insert if needed. It also simplifies stocking to a single high-rating SKU. Browse comparable top-rated options in NRR 33 ear plugs.

If a worker can't seal a SparkPlug from the 6645, what's the fix without retesting the whole program?

Provide an alternative style at the same station — a roll-down foam plug adapts to more canals and most workers can seal it with proper technique. Coach the roll-pull-hold method from how to insert foam earplugs, and keep a reusable earplugs option on hand as a second choice.

Why trust WC Safety
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.
Our standards
Ratings combine published specs, hands-on familiarity, and verified customer data where available; we do not fabricate lab tests.
Affiliate disclosure
Some links are Amazon affiliate links (tag wcsafety04-20); purchases may earn us a commission at no cost to you.
Filed in: Dispenser, Hearing Protection, Moldex, NRR 33, OSHA, PlugStation, SparkPlugs, Workplace Safety
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