From 3m:

The 3M Low Profile Folding Earmuff,NRR 21 dB was designed to be the best way to make sure your ears have adequate coverage. A successful hearing protection product is an excellent tool to have at the job site or shooting range. With the 3M Low Profile Folding Earmuff,NRR 21 dB, receiving a top quality ear muff hasn't ever been simpler. These Protective Ear Muffs from 3M were created using the sturdy and reliable resources that you have come to expect from this extraordinary organization. For a number of years, 3M has been making high quality hearing safety, and the 3M Low Profile Folding Earmuff,NRR 21 dB is the consequence of their dedication to making certain you are using some of the best items that the ear muff community can offer. For a great way to keep your hearing safe and sound, choose the 3M Low Profile Folding Earmuff,NRR 21 dB.