Type: Wireless Wireless Type: RF Power Supply: Rechargeable Ni-MH battery (DC1.2V) x2 Transmitter: DC 12V Operating Time: 10 hours (using Rechargeable battery) Distance: 164 feet Frequency Response: 25Hz-13KHz Weight: 8.82 oz. Transmitter: 9.82 oz. Features: Paging/Call Function - for paging/calling headphone user from base station (transmitter) PLL-stabilized transmission technology- Auto tuning On stand charging Auto power on/off transmitter 40mm drivers for high quality sound Carrier Frequency: 900MHz