Sony MDR-RF5000K 2.4GHz Digital RF Wireless Headphones (Discontinued by Manufacturer) Rf Wireless Headphones Sends Radio Frequency Signals From The Transmitter To The Headphones Features Auto Tuning, Power On/Off & Recharge 2.4GHz Radio Frequency Transmission With Up To A 95-Ft Transmission Range Neodymium Magnet Closed-Type Design Transmission range of up to 100 40mm drivers with PET diaphragms for deeper bass, lower distortion and a wider dynamic range NiMH batteries (included) provide up to 7 hours of playback Frequency response: 20Hz-20kHz Includes transmitter/charger, NiMH battery, AC adapter, UniMatch plug adapter and connecting cable