The black Hesh 2 Wireless Bluetooth Headphones by Skullcandy are for personal listening with mobile devices. They can be used in various audio applications such as for smartphones, MP3 players, computers, tablets, and more. The Hesh 2 wireless headphones have a frequency response of 20 Hz to 20 kHz, and feature a power on/off button to answer and place calls on hold. The on-board +/- buttons let you adjust volume and choose songs. The Hesh 2 are built with a USB port and offer wireless pairing. The rechargeable battery can provide up to 15 hours of music when fully charged. In addition there is a battery status LED indicator that blinks red when the battery is at 10%. A back up cable is included for wired listening.