Ensure seamless access to your favorite apps and smartwatch features with this UltraLast smartwatch replacement battery. The convenient rechargeable format means fewer replacement batteries are required to keep your device in working condition. A simple design makes this UltraLast smartwatch replacement battery easy to install with select Fitbit smartwatch models. Lithium-polymer battery Supplies reliable power to Fitbit Charge smart watches. 3.7V of power Delivers a reliable, long-lasting charge to your electronics. Rechargeable design Delivers power efficiently.