Plantronics' Discovery 640 is a great bluetooth headset: light and comfortable, with long battery life. The small unit weighs in at 9g and even ships with three different ear gels so you can be assured of a snug fit, though like other "hookless" designs, we don't recommend jogging with it.
Pairing is straightforward, and the Discovery 640 is compatible with every Bluetooth-equipped phone on the market.
The device doesn't include noise-cancelling features or automatic volume adjustment, but we had no problems holding conversations in busy areas like underground railway stations. There's a positive of not including noise-cancelling technology, too: enhanced battery life.
The Discovery provides 5 hours of operation on a single charge, which should see you through a couple of days of heavy use between refills. The pack includes an AC charger, a collection of fittings that enable you to use a mobile phone adaptor, and on the road using a AAA cell. All these extras are provided in a small carry case, making the Plantronics kit ideal for a traveller.
A pocket holster that vibrates to alert you to incoming calls rounds out the feature set, making the Plantronics unit a good choice for anyone that spends a lot of time making mobile calls each day.