For noise levels up to 105 dBA, these cap attached with double-shell technology to provide effective hearing protection. Proprietary Twin-Cup design has soft, foam-filled earmuffs. Easy cap-mount design. Earcup pivot points that tilt for optimum comfort and efficiency. Liquid/foam filled earmuff cushions. Noise Reduction Rating (NRR)*: 27 dB. CSA Class AL. *The NRR may overestimate the hearing protection provided during typical use. 3M recommends reducing the NRR by 50% for estimating the amount of noise reduction provided.