Tkasing for Fitbit Alta/Alta HR Wristband with Metal Clasp for Fitness Activity Tracker, Silicon Wrist Bands Replacement Accessories for Fitbit Alta/Alta HR(no Tracker) Free Size:Free sized Fitbit alta hr band fits for 5.5" -- 7.8"(139mm-198mm) wrist.You can move the holes and clasp placement to adjust size,fits almost adult wrist. MATERIAL:durable and comfortable thermoplastic elastomer(TPE) SECURITY BUCKLE:watch buckle secure fitbit on our wrists,free worry falling off problem Comfortable, durable materials make these bands your go-to accessory through exercise, sweat, sleep and beyond NOTE:backup for fitbit alta hr bands or fitbit alta bands, not included fitness trackers of fitbit alta or fitbit alta hr