Sennheiser HDR-65 Supplemental HiFi Stereo Wireless Headphones for HDR-65 (Black) (Discontinued by Manufacturer) Additional cordless headset for use exclusively with Sennheiser RS-65 and RS-60 wireless headphone systems Over-ear, open-air headphone design for great comfort and high-quality sound Center-Lock auto-tuning makes it a cinch to tune to the RS-65/-60 FM transmitter 300-foot range Includes additional BA151 accupack battery, good for 4 hours per charge