Panasonic RP WH20 is a pair of open-air type headphones that use infrared beams to connect to a transmitter, which can be connected to various audio-visual equipment using either a stereo mini plug or pin plug. The headphones are powered by two AAA batteries and have a battery life of approximately 20 hours when using manganese batteries or 40 hours when using alkaline batteries. The headphones have a frequency response of 19-22,000 Hz and a distortion ratio of less than 1.0% at 1 kHz. The transmitter has a power supply of DC 12 V, 150 mA and a power consumption of 4 W.