This pair of headphones & transmitter package is a great solution if your mobile entertainment device does not feature wireless headphone transmitters. The small transmitter module should be mounted in the vehicle so each viewer is in line-of-sight of the transmitter. Simply give the transmitter module power and audio signal from up to two DVD players, game consoles, or similar devices. HP-22IRT headphones feature an adjustable swiveling over-the-ear pad to reduce ambient noise. Each headphone has independent volume control, channel selector switch, and an auxiliary audio input to directly connect an iPod or other device with headphone output. A hardened plastic carry case is included for protective storage. Headphones require 2 AAA batteries. Use HP-12S for additional headphones.