Sony MDRRF925RK Wireless Headphone (Discontinued by Manufacturer) Technical Information--Connectivity Technology--Wireless::Technical Information--Wireless Technology--RF::Technical Information--Cable Length--Not Applicable::Technical Information--Wireless Operating Distance--150 ft::Technical Information--Sound Mode Stereo::Technical Information--Minimum Frequency Response--20 Hz::Technical Information--Maximum Frequency Response--20 kHz::Battery Information--Maximum Battery Run Time--18 Hour::Earpiece--Earpiece Design--Over-the-head::Earpiece--Earpiece Type--Binaural Earpiece--Earpiece Controls--Volume::Earpiece--Driver Type--Neodymium::Earpiece--Driver Size--1.57"::Physical Characteristics--Form Factor--Ear-cup Limited warranty 3 months for parts and 3 months for labor. 150ft max signal reception 900MHz RF wireless transmission, FM stereo sound Induction charging: not direct pin contact Volume control on ear piece, auto power On/Off Charging time approx 16H; Battery life up to 15H, AC Adaptor (DC 12V) included