Fitbit Alta Replacement Accessory Band Silicone strap For Fitbit Alta High Quality (No Tracker) 100% COMPATIBLE WITH FITBIT ALTA - Specifically designed for For Fitbit Alta, (Note: Fitbit Alta Fitness Activity Tracker is not included). Small Size fits wrists 5.4~6.9 inch in circumference. Large Size fits wrists 6.3~8.3 inch in circumferenceSILICON FASTENER RING FOR FREE - COMFORTABLE WEARING EXPERIENCES - it's made of silicone material, very soft and flexible, and no irriation on human skins, you can wear it every day.