Top features: – Wireless Bluetooth technology lets you enjoy your music without the hassle of cables – Integrated microphone lets you answer calls on the move – Foldable headband design for easy storage Wireless Bluetooth technology Sennheiser HD4.40BT Headphones feature Bluetooth technology, allowing you to enjoy your favourite music wirelessly wherever you go. With aptX for high-quality audio playback, they can be synched quickly and easily to your devices using either Bluetooth or NFC pairing. Offering up to 25 hours of battery life, you can still use the headphones even when the battery runs out using the optional 1.4 m audio cable. Integrated microphone Answer calls while on the move without needing to remove the HD4.40BT. The headphones include an integrated microphone in the earcup, meaning that you can make and receive phone calls using the headphones as a headset. Earcup mounted controls allow you to adjust the volume of your music and skip between tracks. Foldable headbandHD4.40BT Bluetooth Headphones have a foldable design, making them extremely portable as they take up minimal space. This makes storage simple using the included pouch. A micro USB charging cable makes it easy to recharge the battery, with a full charge possible in just three hours.