Hd 440 bt wireless the new sennheiser hd 440 wireless offers high quality wireless sound for every day listening on the move the closed back around ear headset features bluetooth 40 and aptx compatibility to deliver true hi fi sound with a satisfyingly dynamic bass its elegantly minimalistic design has been crafted from robust high quality materials to meet the requirements of the street the sennheiser hd 4 series let everyday sound great you can take it with you versatile and vibrant