Walkers FireMax Digital 20dB Muff Black. Walker's FireMax Muff Behind the Neck Specifications for Walkers FireMax Digital 20dB Muff: Manufacturer: Walkers Color: Black Fabric/Material: Polymer NRR: 20 dB Quantity: 1 Size: One Size Battery Type: Lithium Ion Included Accessories: Standard Age Group: Adults Features of Walkers Firemax Behind the Neck Ear Muffs Behind the Neck Design Digital audio circuit Rechargeable Low noise/Frequency tuned for natural sound clarity Full dynamic range HD Speakers for clear balanced sound Sound activated compression Package Contents: Walkers FireMax Digital 20dB Muff Standard Walkers GWP-DFM-BTN: FireMax Digital 20dB Muff Black