Portable wireless headphones, which almost exclusively use Bluetooth (BT) technology, are the latest trend in headphones. And the latest pair to come across is the Sony DR-BT21G. These 'phones use A2DP to convey stereo sound, making them suitable for music listening, and they also include a built-in mic for use as a cell phone headset. At $130, the DR-BT21G is pricier than our favorite pair of lightweight, wireless headphones--the Logitech FreePulse Wireless--but then the FreePulse don't let you take calls.

In a design trait typical of portable wireless headphones and headsets, the Sony DR-BT21G features a lightweight, behind-the-head band that can be folded for easy storage. Although the headband is constructed of cheap-feeling plastic that causes some concerns about durability, it does its job of keeping the headphones in place while not placing too much pressure on the head. Two open-back earphones round out the design, making the DR-BT21G ideal for active applications such as working out. The left cup houses the DC in port, while the right contains the headphone and playback controls: volume and FF/RW/Play/Pause toggles around the edge; power and pairing buttons on the face.

Pairing the DR-BT21G headphones with a Bluetooth (BT) device is a simple matter laid out clearly in the manual, and you can pair up to eight devices, which is pretty impressive. The package doesn't include a BT transmitter, so you'll have to provide your own if you want to pair the headphones with most MP3 players. We used the Jabra A120s, which included its own instructions for pairing and worked just fine. Note that the playback controls (save volume) will only work with devices that support AVRCP, meaning you won't be able to skip or pause tracks if using a transmitter or a BT device without AVRCP. The headphones will automatically mute music--coming from any source--when you get an incoming call or make one yourself.

Audio quality through the Sony DR-BT21G is mixed. On the one hand, the headphones offer good bass response and the open-back design does a decent job of taking the sound outside of the head. In general, mids are mellow, and clarity is decent, but music is brighter than we like, and there's noticeable static hiss during quiet songs (or portions thereof). In other words, the DR-BT21G has nothing on similarly priced wired headphones, but the sound quality is passable if you must do away with wires. Call quality is slightly more troublesome. Our caller complained of drop-outs and garbled-sounding words; in turn, the caller sounded echoey to us. All in all, the DR-BT21G is a suitable set for the gym and for accepting brief calls, but it's no replacement for quality wired headphones and a good BT headset.