For noise levels up to 105 dBA, these cap attached with double shell technology to provide effective hearing protection Proprietary Twin Cup(TM) 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. Color coding to help match attenuation needs. 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. 3M is Leading the Advancement of Hearing Conservation™.