Are you in the market for some Bluetooth headphones that don't look impossibly ugly? It looks Sennheiser is, because they're offering up the MM 400 and MM 450 Bluetooth 2.1 travel headsets for their well-stocked Mobile Music line. These headphones are intended for the pure bliss of enjoying some music, but also for those phone calls we all know you get from time to time. Both the MM 400 and 450 come equipped with an invisible microphone. There's some extra features that Sennheiser throws in just for good measure, so go ahead and take a look.