Tests conducted by the Hammacher Schlemmer Institute proved these wireless headphones to be the best because they achieved the highest score in every metric tested--chief among them is their superior sound quality up to 95' away from the transmitter. The headphones had the longest range of all models, thanks to a proprietary technology that automatically detects the optimal radio frequency when the headphones are removed from the base, providing crystal clear sound transmission up to 20' further than the second place unit. The 40 mm stereo driver produces deep bass frequencies and delivers crisp sound that captures the nuances of recordings, unlike other headphones that demonstrated muted tones. The transmitter serves as the recharging platform, the headphones' inner headband automatically turns off the power when they are removed from your head, and the soft, ergonomic earcup design ensures optimal comfort during extended listening. Multiple inputs on the transmitter allow seamless connection to a television, DVD-, CD-, or MP3-player. The rechargeable battery lasts up to seven hours after a three-hour charge. Includes two rechargeable AA batteries and an AC adapter to power the base. Uses 2.4GHz radio frequency. Base: 1/2" H x 7 1/4" Diam. (11 2/3 oz.) Headphones: (12 oz.)