Amazon.com: Audio Replacement Cable with in-Line Mic Remote Volume control Compatible with Sennheiser HD4.40, HD 4.40 BT, HD4.50, HD 4.50 BTNC, HD4.30i, HD4.30G Headphone and Compatible with Samsung Galaxy Huawei : Electronics
Beats Solo3 Wireless vs Sennheiser HD 4.40 BT Wireless Comparison | Audio46
Sennheiser HD 4.40 BT Headphone review — Becoming intermediate
Sennheiser is launching the HD 4.50BTNC & HD 4.40BT wireless headphones - The Audiophile Man