Fitbit inspire is a friendly fitness tracker for every day that helps you build healthy habits. This encouraging companion motivates you to reach your weight and fitness goals and even enjoy the journey with calorie burn tracking, goal celebrations, sleep tracking and guidance, reminders to move and up to 5 days of battery life. Large fits wrist 7.1"" 8.7"" in circumference. Small fits wrist 5.5"" 7.1"".