Unique grip rings help create a soft, noise-blocking seal for effective hearing protection. Ideal for people with larger ear canals. Poly bag keeps each pair of earplugs clean before use. Noise Reduction Rating (NRR)*: 31 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.