Full closed back design Self adjusting dual headband Neodymium magnet for enhanced bass Independent volume control Low level infrared transmitter Maximum range 7m These stylish infrared cordless headphones offer a wide range of features & are compatible with CD TV audio & video. The transmitter is powered by a 12v 200m A adaptor supplied & the receiver is powered by 2 x AAA batteries not supplied Maplin order code AR42V. Impedance 32andohm.