The Sennheiser Presence 4.0 is a very good headset that me my various Plantronics has made untrue. The sound and the noise reduction function excellently and my interlocutors assure me that the intelligibility is quite improved dramatically during car trips. Have a nice Designkniff I find that you press to turn on any switch but simply pulls the silver element of the microphone towards the corner of the mouth to the front. The problem of the device: the application is a spoiled earhook not does not fold down, so I have not yet managed to apply it with one hand.. That's a real sin in a piece of hardware that is sitting in the car and possibly spontaneously attach must be enabled. Since I use my quasi headset only in the car, I will probably not use the Sennheiser prescence on. Too bad the actual device would have deserved it!