The STIHL Ear Plugs are designed to fit gently into your ear canal. When exposed to loud noises over a period of time, your ears and your hearing can be effected resulting in tinnitus or a simple loss of lower levels of sound. When using loud tools, it is highly recommended to wear Ear Plugs to maintain the health of your ears and your hearing. Made from conically shaped polyurethane foam with good noise reduction, these are comfortable to wear. Before putting them in, gently squeeze them between your fingers and roll them at the same time. When you insert them in your ear, they will gently return to their original shape but fit your ear perfectly. EN 352 rated, SNR 33 H32 M 29 L 29, these plugs have been tested to withstand up to 113 dBA