Another of Plantronics' latest Bluetooth hands-free kits, the Discovery 655 is a great device for those who are regularly on the road. It's very similar to the Discovery 665, but its increased battery life, and the fact that it can be charged by using its extremely handy AAA battery adapter, make it the ultimate solution for the mobile professional.

The best thing about this unit is its charging capability. Plantronics has thought of everything with this package. In the box you get a standard AC adapter, as well as a USB dongle for charging via a notebook or PC. However, the real gem is the included charging cradle that supports a AAA battery. It's brilliant for those who are regularly away from AC power as it allows a user to carry a small stockpile of batteries so that the unit can be charged anywhere.

When running while connected to this adapter, the unit can supply 10 hours of talk time, which is huge compared to the average of six or seven hours that we typically see. However, without the cradle, Plantronics quotes a talk time of only 3.5 hours and 80 hours of standby time.

The other feature of the 655 that Plantronics is heavily marketing is its vibrating function. When docked in the nifty pocket sleeve, the unit will vibrate upon receiving an incoming call. This is a pretty funky feature that means you can have your hands-free connected to your mobile and be listening to music without missing a call.

In our tests, the 655 produced good audio quality, during incoming and outgoing calls. Callers reported the voice quality to be crisp and clear. While a little more volume on the incoming audio would be welcomed, it's satisfactory for most uses.

As with the other models in this series, the controls and the interface are extremely basic. Almost everything is done using the main control button. This includes answering and ending calls, rejecting them and bouncing them between the phone and headset. The only other buttons are for controlling the volume.

Just like the Discovery 665, the 655 doesn't have a compulsory ear clip (although one is included in the package). Instead, it's supported by a rubber clip as it slips into your ear canal. It weighs only 9g and this is perfectly comfortable. It makes the 655 a great unit to use as you can slip it in and out with no hassle. This also makes it less conspicuous than most other hands-free kits on the market, which is a boon considering how strange some older models look. Several ear pieces are provided, so you can tailor the fit to the shape of your ears.

The design of the 655 is slim and stylish, with an angular black and silver body that looks quite modern. There is also a small LED ring around the control button that changes colour to indicate whether the kit is paired or in pairing mode.