The ath-cks550xbt wireless in-ear headphones feature 9. 8 mm solid bass HD drivers specially designed to fit within the headphones' compact housings, giving you a comfortable listening experience that doesn't sacrifice sound quality. The accurate sound reproduction is furthered aided by Bluetooth wireless technology that Works with both the standard SBC codec and the higher quality AAC codec. In addition, the headphones' large-diameter sound tubes extend frequency response for excellent wide-range audio with invigorating bass. The headphones are equipped with an in-line mic and controls, allowing you to answer calls, adjust volume and handle playback of music and videos on smartphones and other devices. The neckband design conveniently situates the 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 Secure-fit battery clip. The internal Lithium polymer rechargeable battery provides up to seven hours of continuous use (200 hours in standby mode) on a full charge. The ath-cks550xbt headphones come with four sizes (XS, S, M, L) of interchangeable ear tips, a 30 cm (11. 8") USB charging cable and a protective carrying pouch.