IR HEADPHONE About 72 Hours Listening Time Dim Led Shined to Indicated Power Storage Use 2x AAA Batteries Operation IR TRANSMITTER Transmission Distance up to 20FT Do Not Affect Corded Headphone Operation Compatible with SDV-17A*, SDV-37S* & SDV185-S** * Wireless headphone supports  AC/DC & car adapter for SDV-17A and SDV-37S only **  Wireless headphone supports AC/DC Charger, Car Charger & Rechargeable battery for SDV185-S