For use with Power Acoustik(R) Mobile A/V systems; 2-channel, 900 MHz wireless headphones with swivel earpads; Selectable program source inputs; Auto mute control; Built-in monitoring function; MP3 player input via 3.5 mm input; On/off switch saves battery life; Variable volume control; Auto level control; Requires 2 AAA batteries per headphone; Includes EVA hard carrying case and wireless transmitter;