The Fitbit Charge Wireless Activity Wristband in Black, size Large, is a brand new sealed fitness technology device perfect for indoor and outdoor activities like gym training, crossfit, swimming, pilates, running, and jogging. Made of durable plastic material, this activity tracker by Fitbit is designed for both iOS and Android operating systems, making it compatible for a wide range of users. The sleek black color and wireless feature make it convenient and stylish for unisex adults looking to track their fitness progress in English language.