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Fitbit announces the Flex wristband, a $100 fitness tracker to take on the Jawbone Up

You know what they say, right? You can never have too many fitness trackers. After coming out with two health monitors back in September, Fitbit is back with a third product, the Flex -- a water-resistant wristband seemingly designed to compete with the Jawbone Up. (In PR speak: "Fitbit understands that one tracker does not fit all.") Like other Fitbit devices, it counts calories, steps taken and distance covered. Unlike the others, however, this does not count flights climbed. In any event, the band automatically sends that data to a personalized website over Bluetooth. You can record your food intake, too, but you'll have to do it manually using either the website or one of the company's mobile apps.

The Flex tracks your sleep quality as well, but the approach here differs from other Fitbit products: whereas the Fitbit One and Fitbit Zip have a key you can press to enter sleep mode, the Flex has no buttons at all, so your only recourse for logging sleep is to use the app or website. We have to say, that sounds like a bit like a case of form over function: the Up can detect when you're sleeping, as can the pricey new Basis band. The good news is that the battery life seems decent: Fitbit says the Flex can last between five and seven days on a charge, and that's despite having a Bluetooth 4.0 radio inside. For comparison's sake, the Jawbone up is rated for up to 10 days but then again, you have to plug it in every time you want to sync, and the cap covering the charging piece is easy to lose. So, that's something to keep in mind. In any case, if you prefer the wristband form factor and want something less expensive than the Up, the Flex costs $100 and is up for pre-order today, with shipments expected to begin sometime in the Spring.

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