Your hearing health should never be neglected. SureFire EP4 Sonic Defender Plus will protect your hearing from Noise-Induced Hearing Loss (NIHL) without hindering your ability to hear everyday sounds or conversations in noisy environments. Its triple-flanged stem offers a Noise Reduction Rating (NRR) of 24 dB. Safe sound levels can pass into the ear canal, while potentially harmful noises (above 85 dB) are reduced through SureFire's proprietary noise-reducing filter. EP4s come with attached filter caps that can be added for extra protection, blocking out lower-level noise, such as that on an airplane, where hearing ambient sounds or conversations isn't essential. Sonic Defenders are made from a soft, durable, hypoallergenic polymer that provides all-day comfort and longer product life.