Headband headphones wireless headphones freedom of sound reception transmission range ca 100m battery run time ca 20 25h modulation type fm stereo total harmonic distortion at 1khz 07 choice of 3 rf channels wall mountable transmitter includes rechargeable nimh aaa batteries series sennheiser rs line type of fitting on ear transmission mode cordless features padded headband adjustable headband sensitivity 106 dbmw impedance 24 ohm frequency resp