THE SENNHEISER HD 2 SERIES - Supreme Musicality To Go. The new HD 2 SERIES is elegantly minimalist in design, yet tough enough for a life in motion. It lets your music shine wherever you are. The HD 2.10 is ultra slim and sturdy. With a closed-back on-ear design, it provides a powerful bass without compromises. The HD 2.20 is slim, foldable, lightweight and features a single-sided, tangle-free cable, with a built-in one button smart remote. The HD 2.30 is lightweight, robust and foldable. It delivers a detailed sound reproduction with a powerful extended bass response and ear pads cushioned by the comfort of the premium leatherette.