3M Foam Earplugs 1100, Uncorded, Noise Reduction Rating (NRR) 29 decibels (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), CSA class AL. 3M 1100 uncorded foam earplugs feature soft, hypoallergenic polyurethane foam, a smooth, dirt-resistant surface for better hygiene and a tapered design to fit comfortably in a wide range of earcanal sizes.