The 3M™ Peltor™ H7P3E Optime 101 Helmet Attachable Earmuffs are designed to work with slotted hard hats and have a noise reduction rating of 24 dB. These earmuffs provide solid hearing protection for noise levels up to 101 dBA and are color coded for easy compliance checks. These H7P3E Optime 101 earmuffs have a 24 Noise Reduction Rating (NRR 24 db) CSA Class A. NRR: NRR 24 dB Style: Helmet Mount Manufacturer SKU: XH001651245