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 steal the mojo from competitors like Nike’s Fuelband and the Jawbone Up. Now the Flex is out in the wild, and users can be the judge.

Bluetooth 4.0 is used to connect the silicon wristband to an Android device or iPhone. It does everything the typical fitness tracker accomplishes: counts calories and steps, monitors sleeping, and lets you share stats with friends to keep you motivated. The actual exercise is still on you, though.

https://www.youtube.com/watch?v=yggn7P4pRUw

Newer Android devices with NFC can quickly view the Flex’s stats with a simple tap of the smartphone’s screen. Bluetooth is also used to pair the Flex on both Android and iOS.

The band itself is waterproof and capable of lasting for about five days on a single charge. Colors are Black, Slate, Teal, Tangerine, and Navy, with additional two-tone color combinations available for a higher price.

“We are incredibly excited to launch the Fitbit Flex,” says James Park, CEO and co-founder of Fitbit. “Fitbit has worked hard to develop the most seamless, versatile, and accurate activity trackers and with the addition of Flex, we truly have a product line that fits any lifestyle. Utilizing the latest technology—including Bluetooth 4.0 for mobile devices—Fitbit has developed a wristband tracker that offers the elements our fans love in a brand new form factor.”

Sites like TechCrunch, The Verge, Wired, CNET, and Engadget all have reviews of the Fitbit Flex, and they all seem to be pretty positive.

• SourceFitbit