The HD 4.40 BT is a wireless headset employing Bluetooth 4.0 and aptX technologies to deliver exceptional wireless Hi-Fi sound. It features NFC for simple pairing of compatible devices. This new headset offers ease of use and convenience thanks to intuitive ear-cup mounted controls for changing tracks and for making calls via the integrated microphone. Wearing comfort is assured by their ergonomically designed ear pads. The HD 4.40 BT has excellent battery life, letting listeners enjoy wireless sound for up to 25 hours. A battery-free listening mode is also possible via a supplied detachable cable.