WSA-5RP Wireless Surround Sound Rear Speakers Kit with 2 X 50W Amplifier Built-In, 5.2G / 5.8Ghz Dual Band Selectable, Total 106 RF Channel Auto Switching. Included Components Wireless Transmitter, Receiver, Speaker Line Level Input, Stereo RCA Input, options for passive bookshelf/rear surround sound speakers and a powered/active subwoofer.