Fitbit Flex 2 is an ultra-slim, water-resistant-proof fitness wristband with a removable tracker that fits into bands, bracelets or pendants—so you can effortlessly track all-day activity, exercise and sleep in a style that’s all your own.
Description taken from: https://blog.fitbit.com/introducing-fitbit-flex-2/#:~:text=Fitbit%20Flex%202%20is%20an,style%20that’s%20all%20your%20own.