Protects hearing from particularly harmful impulse sounds (from 82 db), while amplifying other sounds, such as human voices or nature sounds. 6-step volume control. With adjustable and foldable headband and audio input for connecting a radio or cell phone. SNR attenuation value: 25 db complies with EN 352-1 and EN 352-4 standards. Operates on 2 AAA batteries (please order separately).