Search for non-electronic hearing protection on the market and you’ll probably notice right away that SureFire EarPro® Sonic Defenders® aren’t your basic, mass-produced hearing protection. Their patented EarLock outer ring gives them a distinctive look that truly sets them apart from the myriad run-of-the-mill, disposable, foam, or flanged earplugs.

SureFire EarPro features patented EarLock design
All SureFire EarPro hearing protection features a patented EarLock design that improves hearing protection by ensuring a custom fit.

But the EarLock retention device isn’t merely a styling exercise. It is a key ingredient to what makes SureFire EarPro the most effective mechanical hearing protection available. There’s a compelling history behind the development of the EarLock. Richard Smith, SureFire Vice President of Communications and head of the EarPro division, is happy to tell it.

“In the 1990s, custom earpieces made from ear impressions were the best way for a hearing medical specialist to make in-ear earpieces,” Smith says. “These custom ear impressions were individually molded and custom ground by the hearing specialist to the size for each person. The problem is that these custom impressions/molds are costly — $200 to $300 per pair, time-consuming, labor-intensive, and have to be made by a trained professional. The process involves at least two well-trained specialists, molding material, specialized instruments, and more. The time and expense put this type of hearing protection out of the cost range of most law enforcement and military, and others who need the highest-quality hearing protection. We made it our mission to change that.”

Enter the SureFire EarLock, a device that helps to give Sonic Defenders a custom fit at a fraction of the price while ensuring maximum effectiveness of SureFire’s scientifically engineered noise filtration systems. The EarLock increases comfort for EarPro wearers in multiple ways, but its key benefit is that it helps to ensure proper placement of the stem in the ear canal for maximum noise reduction.

SureFire EarPro retention lock diagram

The result of more than 10 years of research by Dr. Diann Y. Smith Au.D., the EarLock is a flexible, injection-molded, spring-type polymer concha ring.

“To perfect the design and ensure a proper fit for the majority of the world’s population, more than 10,000 custom ear impressions were made and studied,” Richard Smith says. “The whole earpiece had to be flexible enough to fit itself to the concha bowl of the ear and the ear canal. It had to be soft enough to be comfortable for long hours of wear and to protect against violent hits to the ear. It also had to be firm and flexible enough to hold the earpiece, the hearing protection, and/or communications in place, even in violent head movement.”

Extensive R&D led to the development of the EarLock, a concha ring locking design that follows the underside of the ridges of the ear’s conchae bowl from bottom to top. The EarLock contacts the ear at up to seven grab points, following the underside ridge of the concha bowl from the bottom of the bowl of the pina to the top of the ear (see Figure 1 above). But the average person wearing EarPro with a Medium size Earlock — the most common size — may only utilize four to five of the seven grab points to attain proper fitment.

SureFire EarPro features patented EarLock design
The EarLock holds SureFire EarPro firmly in place to prevent it from falling out due to recoil or other concussive effects.

The benefit is hearing protection that fits right and delivers all-day comfort for the wearer. Unlike most push-in hearing protection, the EarLock prevents the wearer from pushing the stem of the EarPro too far into the canal, which can damage the eardrum. Once seated, it also secures the stem from falling out of the ear canal, thus stopping harmful noise from “seeping” past the stem and causing hearing damage. The latter is critical, as harmful noise that enters the ear through a pinhole-sized opening can cause the same damage as if no hearing protection is worn. Both are common issues with the majority of push-in hearing protection on the market.

The EarLock completes a SureFire hearing protection formula that incorporates many innovations in each EarPro model, such as the ergonomically engineered, curved stem that is used in the Sonic Defenders EP4, the gold standard in non-electronic hearing protection. SureFire’s curved flanges follow the natural path of the ear canal, eliminating painful “hot spots” that commonly occur during prolonged use of hearing protection that uses poorly designed straight flanges. The straight flanges are often too long to fit entirely in the ear, and have nothing like the EarLock to hold them in place, thus users are more likely to adjust the positioning of the stem in the ear to eliminate discomfort. This constant readjustment can break the seal of the earplug in the ear and increase the chance of hearing damage.

“Our EarLock and curved stem designs work so well that OTTO Communications, the largest U.S. manufacturer of acoustic tube two-way radio headsets, sells the EP4 for their acoustic tube one-, two-, and three-wire headsets and for a version of their boom mic headset,” Smith says. “The EarPro EP series is the only standard hearing protection of this type. They can be adjusted to full-block for maximum protection simply by inserting the attached filter plugs, or you can leave the filter plugs out for protection from impulse noise and harmful constant noise above 85 dB. They are also ideal for two-way radio, electronic hearing/hearing protection for the majority of acoustic tube headsets sold.”

SureFire EarPro sizing chart

Every SureFire EP model is available in small, medium, and large EarLock sizes. The aforementioned Medium size fits the vast majority of users, but a simple measurement of your Concha bowl (see Figure 2) is all it takes to determine the right size for your ear.

“SureFire EarPro provides that same custom fit along with our best-in-class Noise Reduction Ratings [NRR] for around $15, making high-quality hearing protection affordable for everyone from military operators to construction and industrial workers,” Smith says. “No other non-electronic hearing protection brand provides our level of performance, durability, and versatility.”

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