Fitbit has just announced that it will be releasing a new device (bringing their total device count to 3) called the Flex. It is a waterproof wristband that clearly competes with the Jawbone UP 2. It tracks activity but unlike it's other products, the Flex does not measure altitude (aka number of steps climbed). It then connects to your smartphone via Bluetooth to upload data back to the Fitbit mothership.
It also tracks your sleep but unlike the other Fitbit devices, it doesn't have a button to engage sleep mode. To turn on sleep mode, you have to use Fitbit's smartphone app. Jawbone auto-detects when you sleep.
A single charge should last 5-7 days (the UP lasts about 10). The only positive about the Flex (compared to the Jawbone UP) is the cheaper price, $100. The device should be available sometime this spring.
Considering the stiff competition in the health tracking market, I am surprised Fitbit is releasing something this bland and boring.
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