The Fitbit Flex's core features are similar to most other wristband-trackers: it measures your sleep and steps and helps you log how many calories you eat.
One of the Fitbit Flex's most useful features is the five LED-lights that show you how close (or far away) you are from reaching your daily step-goal.
The Flex is a great tracker, however, like many wearables, it's not faultless. The device isn't the easiest to wear and the battery life doesn't seem as long as some of its competitors, like the Jawbone UP .
Even with its faults, the Flex is still a great device - it's the best selling activity tracker on the market for a reason and we give it a solid score of 70/100.