The first Bluetooth headset featuring VoiceMax dual-microphone technology, Sennheiser's VMX 100 certainly packs in plenty of features. Its dual-microphone system -- one to emphasise your voice and the other to remove noise -- is the first of its kind, while it also boasts a 3D ball joint for extra comfort, and a talk time of up to five hours.

VoiceMax technology is the highlight of the VMX 100. Sennheiser claims the unit uses two microphones and advanced Digital Signal Processing (DSP) to distinguish between your voice and background noise. The technology then adjusts the amount of noise it removes according to the environment you are in. Although our caller's voice was extremely crisp and clear with notable volume levels, the VMX 100 doesn't completely eradicate background noise -- our callers still complained of minor instances in this regard. Despite this, the general quality of calls is superb, and is perhaps slightly better than the Z9.

Design wise, the VMX 100 is quite bulky. It has a large behind-the-ear piece and a convenient 3D ball joint; when folded open, this automatically turns on the unit. Despite the bulky size, it's fairly comfortable to wear, sitting neatly on top of your ear. The combination of black rubber and titanium-coloured plastic is a nice touch and looks business-like, while the controls are nearly laid out and are easy to access when worn. Our only complaint with the design is that the unit really stands out on your ear, and this may not suit everyone.

The VMX 100 is quite easy to use, with a call handling button and a volume button, the only two controls on the unit. Folding out the microphone boom automatically puts the unit into pairing mode and once paired, functions are simple and easy. Press the call handling button to answer a call, hold it to reject the ball, and press it again to end the call. Alternatively, you can simply close the microphone to end a call. You can also redial your last number by holding the call button for almost two seconds. Additional functions include activating voice dialling (provided this is supported by your phone), transferring a call from the headset to your phone and muting the microphone.

Sennheiser claims the VMX 100 has up to five hours of talk time and up to 100 hours standby. Conveniently, both a USB cable (for charging via a PC or notebook) and an AC adapter are included in the package. To top off the package, the VMX 100 comes with a two-year warranty.