Of the many activity-tracking wearable accessories we've covered over the past few years, Fitbit's Flex was one of our favorites. Now the company is back with Force ($130), an updated version of the band that adds features while maintaing a very similar look and functionality. Now, instead of a tap-controlled sensor that can fit into one of two bands and must be removed to be charged, you get a single band with an integrated tracker. Tap controls…
