Optime Earmuff Cap-Mount HeadsetCap-mounted earmuffs are designed to fit most hard hats. Liquid/foam-filled ear cushions provide a high level of comfort for long-time wear. Significant noise-reduction properties block out exterior noises and allow wearer to concentrate. Earmuffs are color-coded for compliance sighting. Ear Cushion Material: Liquid/Foam; Noise Reduction Rate (NRR): 24 dB.