The X-Series attachment ear muffs are 3M's latest advancement in hearing conservation. New technologies in comfort, design and protection all come together in this groundbreaking earmuff line. The X5A earmuffs offer the highest NRR (31dB) for an earmuff on the market which makes them ideal for very high noise situations. The high attenuation delivered by X5A earmuffs is possible as a result of a combination of advanced technologies including: newly designed spacers, specially formulated earcup liners and innovative foam contained in the cushions. It Features: an electrically insulated wire headband, often referred to as ?dielectric?. Replaceable ear cushions and foam liners (hygiene kit HYX5 - Product Code 140229). Noise Reduction Rating (NRR) = 31 dB. CSA Class AL. SNR = 36dB, High Frequency = 36dB, Medium Frequency = 34dB, Low Frequency = 26dB.