With the ATH-CKR55BT's newly designed 10.7 mm drivers and Bluetooth® wireless technology (including access to the high-quality aptX and AAC codecs) you get powerful, full-range audio that goes wherever you go. The headphones also feature an in-line mic and controls, allowing you to answer calls, adjust volume and handle playback of music and videos on compatible smartphones and other devices, plus a built-in amplifier to enhance the audio's depth and resolution. Machined brass stabilizers absorb unwanted vibration for clearer mid and high frequencies. The neckband design of the ATH-CKR55BT conveniently situates the in-line mic and controls for easy access and places the battery case on the upper back where, if desired, it can be attached to your shirt collar with the included clip. Also included are four sizes (XS, S, M, L) of interchangeable eartips, 30 cm (11.8") USB charging cable and a protective pouch.