Description:
Initially the band that you get with the Flex is the only one that you can use. However, you can replace your existing color which means that not only can you change the color of your Flex from time to time, but you also have spare or replacement bands should your existing one break
Fitbit Flex Wristband sizing
Large Replacement Bands: 6.3 - 8.2 inches // 161 - 209 mm long, 0.6 inches // 13.99 mm wide