Sleek black Sennheiser HD 4.40 BT headphones combine a closed‑circuit design with a foldable frame and padded headband for comfort. Bluetooth 4.0 delivers up to 25 h of music, while an integrated 3.5 mm jack keeps wired use possible. A Li‑Po battery charges in about two hours, LED indicators show status, and the omnidirectional mic ensures clear calls.