Pyramex's Venture Gear Sentinel Electronic Earmuff features slim profile ear cups, fold-away, padded headband, and a front facing microphone. The muff helps amplify hearing, while compressing harmful sounds and reducing them to a safe level. It also has an auto shut-off after four hours, 3.5 mm AUX jack for use of MP3 and mobile devices, and height adjustment to fit all sizes. Nrr 26 dB Type Electronic Earmuff Color Powder Blue/Black Style Over the Head Series Sentinel Muff Material Polymer Quantity 1 Pair Battery Size AAA