Sony MDR-RF960RK 900 MHz RF Wireless Headphones with Auto Tuning (Discontinued by Manufacturer) 900 Mhz Transmission Closed-Type Headphone Transmits Through Walls, Ceilings & Floors 30Mm Driver For Deep Bass Comfortable Leather-Like Ear Pad RF wireless headphone system using FM transmission system Up to 150-foot transmission range with auto frequency tuning/reception Lightweight closed-type headphones with 30 mm drive units for deep bass; volume control on headphones; automatic on/off headphone function Self-adjusting headband for precise and comfortable fit Up to 24 hours battery life using 2 AAA batteries; includes 2 NiMH rechargeable batteries with up to 15 hours' use