The aptX audio codec allows for higher quality wireless music streaming compared to standard Bluetooth thanks to better compression.
Both the MM 450-X and MM 550-X feature Sennheiser's NoiseGard 2.0 active noise-cancelling technology, plus TalkThrough for one-touch activation of the external microphone.
Also on board is SRS WOW HD sound processing technology. The bluetooth headphones can also be folded-up for added portability.
There are also MM 400-X and MM 500-X Bluetooth headphones, which also offer aptX Bluetooth playback but don't have active noise-cancelling technology.
The Sennheiser MM 450-X and MM 550-X are due out worldwide from March.