For loud environments, these hard hat attached earmuffs provide effective hearing protection. • Hard hat attachment design allows for easy use with most hard hats • Foam filled ear cushions • Color-coding for compliance sighting • Noise Reduction Rating (NRR)*: 24 dB. CSA Class A *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™.