Picking the right wireless headset to accessorize your iPhone or other cell phone can be a pain in the, well, ear. Offering the right mix of size, weight, and audio quality is hard to do, and the BT400 GL In-ear Bluetooth Headset manages to pull the first two off without a hitch, but doesn't fare quite as well with audio.

The BT400 GL is amazingly small. So small, in fact, that it almost makes my second generation iPod shuffle seem kind of bulky. It measures 1.53 x .66 x .47-inches, and weighs only 8.5 grams. Instead of fitting over your ear, it uses an in-ear bud that holds the unit in place and also pumps other people's voices into your head without lots of extra noise.

The BT400 GL looks small even compared to an iPod shuffle.

Since the BT400 is so light weight, I found it to be really comfortable. After a couple of minutes, in fact, I didn't even notice it was in my ear until my phone rang. It also includes three different sized ear pieces, so most people should be able to find a fit that's right for them.

Although small, the three surface buttons on the headset are easy to locate. They are aligned in a row, and the end buttons are flared so it's easy to find them with your finger.

The portable cradle charges the BT400 on the go.

RadTech claims the battery life on the BT400 is 350 hours in standby mode, and 15 hours talk time. That super-long standby time comes in part from an ingenious little portable cradle that includes its own power supply. When the headset is in the cradle, it recharges from the unit's built-in battery.

The cradle also includes a vibrate feature, so you can tell when you are getting a call even if the headset isn't in your ear. That's a handy feature if your cell phone isn't in your pocket and is set to silent mode.

The BT400 GL and its cradle.

Light weight, compact, comfortable, and crazy-long battery life. What's not to like? Unfortunately, the audio quality.

Just to be clear: I had absolutely no problems hearing anyone I was talking to. Everyone sounded clear and easy to understand. The real problem was that everyone listening to me had a hard time hearing what I was saying.

The common complaint was that I sounded muffled or distant. One guinea pig, er, friend asked if I was using a speaker phone. I tested the audio quality with an iPhone, Motorola Razr v3, PowerBook G4, and MacBook Pro all with the same results. This was the one disappointment for me, and it especially stung because every other feature on the BT400 is fantastic.

The Bottom Line
The BT400 GL In-Ear Bluetooth Headset has so many great features: fantastic battery life, portable charger cradle, comfortable fit, and easy to use. The audio quality is the only component that needs some help -- and unfortunately, that's the thing everyone you talk with will notice first.

If your primary goal is to use a comfortable Bluetooth headset that can go for a long time between charges, this is the best option around. If you are more concerned with audio quality, however, the BT400 probably shouldn't be your first choice.