Sabrent Weather Resistant 900MHz Wireless Indoor/Outdoor 150 FT 4 Speaker System with Remote and Dual Power Transmitter (SP-NELO4) Powered by 900MHz Phase Loop Lock circuitry which automatically locks in and keeps the audio signal clear and strong Has a superior performance range of up to 150 feet with no line of sight limitations The system transmitter supports all types of 3.5 mm audio inputs including RCA inputs for home theater receivers, MP3 players, computers, iPod, iPhone, and iPad Allows you to charge iPod / iPhone / USB cell phones / USB MP3 players