San Francisco-based Fitbit has commercially launched its first wristworn activity and sleep tracking device, Fitbit Flex, which it first announced at the Consumer Electronics Show in January. Fitbit ...

The Fitbit Flex has officially gone on sale for $100 online and in U.S. retail stores. We saw the “OG fitness-tracking dongle” at CES earlier this year, where it was clear that Fitbit was trying to ...