No.1 doctor recommended. Made with comfy cush comfort foam. Ultimate comfort. Highest noise reduction rating. NRR 33 dB. Noise Reduction Rating: 33 Decibels (When used as directed). The range of noise reduction ratings for existing hearing protectors is approximately 0 to 30 (High numbers denote greater effectiveness). Extreme noise blocker. The level of noise entering a person's ear, when hearing protector is worn as directed, is closely approximated by the difference between the A-weighted environmental noise level and the NRR. Example: 1. The environmental noise level as measured at the ear is 92 dB (A). 2. The NRR is 33 decibels (dB). 3. The level of noise entering the ear is approximately equal to 59 dB (A).