Features • RF wireless headphone system using FM transmission system • Up to 150-foot transmission range with manual 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 28 hours battery life using 2 AAA batteries; includes 2 NiMH rechargeable batteries with up to 18 hours' use