The Good: The Fitbit Flex is a simple way to track steps, sleep, and calories. The Flex's strap design makes it light and comfortable to wear. It also offers handy Bluetooth syncing, and Fitbit\u2019s platform gives plenty ways to analyze your stats. The Bad: Clasping the Fitbit Flex\u2019s strap shut is tricky. Direct syncing is only available with the iPhone, the Samsung GS3, and the Galaxy Note handsets. The Bottom Line: A long list of features and a comfortable fit make Fitbit\u2019s new Flex the best fitness tracker you can buy. Editors' note (August 29, 2016): Fitbit has announced the Flex 2, an updated fitness tracker that's smaller, water-resistant and more fashion-forward than its predecessor. The Flex 2 replaces the original Flex reviewed here in Fitbit's lineup. The $99.95 Fitbit Flex is the newest personal fitness tracker in the company's lineup. While the Flex isn't without some flaws, the gadget is the most complete product of its kind you can buy. It can track steps taken, sleep quality, and it syncs data wirelessly with PCs and Macs automatically. Comfortable to wear, the Flex can communicate directly with iPhones and select Android smartphones, and is water-resistant as well. Going head-to-head with other wristband-style exercise products such as the and , the Flex offers more features and convenience at a lower price than those more expensive devices. Design When I first picked up the new Fitbit Flex, I initially considered its unadorned surface and clean, ring shape spartan. After all, the device lacks a real screen capable of displaying alphanumeric characters. Instead the Flex sports a thin sliver of a display cut from smoky dark plastic. Underneath the plastic sits a row of five tiny, white LEDs that blink to indicate the Flex's status. The Flex's flexible rubbery band, however, masks the product's true complexity. Inside a small pouch on the strap's underbelly you'll find the real brains of the operation, a smooth plastic pebble that contains all the Flex's electronics. In fact, the LEDs visible from the band's surface are actually located on this little gizmo. Indeed, half the size of the current Fitbit One and Fitbit Zip, the new Flex is Fitbit's smallest tracker yet. Other than its LEDs and a Fitbit logo, the only other features you'll find on the tracker is a line of metal contacts. These are used for charging the Flex's rechargeable battery through the supplied USB cable and socket adapter. Popping the Flex into its band is easy, and the tracker even has an arrow indicating which direction it should be inserted. Attaching the band to my wrist is another situation altogether. The Flex has nine oval holes on one side of its wrist strap, and two hard pegs on the other.To button up the band you snap these pegs into the Flex's notch-shaped holes. In my experience it's a tricky process that requires a lot of force. Call me a wimp, but I even injured myself attaching the band; I mashed my thumb too hard against my wrist. Fitbit says that it's aware of this issue and that it should only affect preproduction units such as mine. One benefit of the Flex's tight wrist lock is that it's unlikely to become unhooked. If you spend a lot of time around water or in the rain, the Flex has your back. The device is fully water-resistant and is designed to shrug off exposure to splashes and short immersions in liquid. As a result I was able to both shower and wash dishes with the Flex strapped to my wrist daily. It's a good thing, too; the Flex is so light and comfortable, I often forgot it was there. In my opinion, the Flex is more comfortable to wear than the , another well-designed and highly ergonomic wristband tracker. Features and performance The most recent fitness tracker from Fitbit, the Flex offers almost all the same features as the company's One product. It relies on an internal accelerometer to record the steps you take, the calories you burn. The device calculates this by factoring in your age, height, and weight, which you punch into a linked Fitbit account online. Another trick the Flex takes from the One is its ability to track the length and quality of your sleep plus how many times you woke during the night. The Flex is much more convenient gadget for sleep tracking, though, since it's already strapped to your arm. That means you can wear it straight to bed and don't have to mess with a separate armband like you do with the Fitbit One.