The Kharaband is a high-quality, contemporary wristband that provides extra battery power to ALL wrist-based wearables. There are 4 premium batteries inside that are load balanced to continuously charge your wearable allowing up to 3 times longer battery life on a single charge. Made of soft silicone, Kharaband shapes comfortably around the wrist and the strap is segmented to allow a safe amount of flex between batteries. It is water resistant and sealed for protection made with four high-quality batteries that will last 3 years or 5,000 hours. There are 4 adjustment positions fitting mosts wrists between 140-210 mm.