Audiovox Acoustic Research AWD204 On-Ear Wireless Stereo Headphones (Black) (Discontinued by Manufacturer) 900MHz digital wireless sound with crystal-clear reception through walls, floors and ceilings up to 150-feet Compatible with iPod/iPhone; Digital tuning on transmitter and headphones Frequency response: 20Hz-20kHz; Distortion (THD): &lt; 1% Battery type: two AAA rechargeable (included); battery life: Up to 6-hours between charges Transmitter audio input: 3.5mm stereo jack