3M™ earmuffs feature durable, lightweight construction of non-conductive, dielectric plastic that mounts to most hard hats without an adaptor and easily swing out of the way when not in use. Benefits •Lightweight, durable plastic construction is non-conductive and dielectric for tough environments. •An "at-rest" position eliminates contact with other gear to reduce contamination and distortion. •Works with most slotted hardhats •Noise Reduction Rating* NRR 21 dB. CSA class B