Specifications 2.4GHZ Digital Ultra High Frquency (UHF) Technology 31-Channel Auto Frequency Hopping System for optimum transmission Electronic Volume Control Low Power Indicator Notification on Headphone Speed Charging Mechanism Operation Distance: Up to 30 meters (Open Area) Support Corded Headphone Application with 3.5 mm Audio Cable; Frequency Response: 30Hz to 20KHz; S/N Ratio: >75dB Compatible with DVD players, CD players, iPod, MP3, TV sets, VCR, Hi-Fi system and radio