Multi-Position Earmuffs EachNoise Reduction Rating* NRR 20 dB (CSA class B) when the band is worn over the head. NRR 22 dB (CSA Class B) when the band is worn under the chin. NRR 22 dB (CSA Class B) when band is worn behind the head Multi Position Earmuffs feature durable, lightweight construction of non conductive, dielectric plastic that can be worn over the head, behind the neck or under the chin. Manufacturer: 3M Product Name: Multi Position Earmuffs Model: EARM1000