Sony MDR-IF245RK Wireless IF Headphones

Sony MDR-IF245RK Wireless IF Headphones Wireless infrared headphones for cord-free listening. Connectivity Technology: Wireless 40mm driver units for expressive sound Self-adjusting headband for easy to use comfort Muting function reduces noise when out of range Up to 8 meter (26 feet) reception range Connectivity technology: Infrared wireless AAA alkaline batteries (not included) can also be used as alternative power We purchased these headphones on November 2013; we opened the box and looked at everything, and then never used