DAPRIL Hydration Bladder, Leak Proof Water Reservoir, Military Water Storage Bladder Bag, BPA Free Hydration Pack Replacement for Hiking Biking Climbing Cycling Running (3L Blue) (Advanced) Premium Design: Slim and lightweight body with 0.96" OLED screen, wrist sense design, cable-free charging with built-in USB plug, and long battery life; all to make your life easier. All-day activity tracking:Track steps, distance, calories burned, active minutes, you can check daily activity and time on OLED display. Built-in USB Plug: Built-in USB plug make it easy to charge with any USB block and computer; no charging cable and dock needed; one single charge gives you up to 7 days of battery life.