Review: The Fitbit Flex wristband bests its closest competition AT A GLANCE The Fitbit Flex matches the core functionality of the company's other socially-connected digital pedometers, but it's worn on the wrist. Its Bluetooth syncing and durability help it best competitors like... I’m writing these words at 2.5 miles per hour. For a couple of years now, I’ve worked on a treadmill desk—and while my number one motivation is healthiness, a secondary and unexpected inspiration to get the treadmill running is simply this: I need to get more steps than my friends do. I’ve used (and occasionally reviewed) a variety of fitness tracking devices, among them various models of the Fitbit (the Ultra, the Zip), the Striiv, and the Jawbone Up. To some, they’re glorified pedometers; to me, they offer plenty more: These devices can track things like your steps walked, distance covered, stories climbed, and sleep … slept. And they let you see how your numbers stack ...