ETT (Eco Tech Time) Solar Drive Radio Controlled watch. Key Details Brand: ETT Eco Tech Time Technology: Solar Drive Radio Controlled, meaning it is powered by light and automatically adjusts the time via radio signals from an atomic clock. This eliminates the need for regular battery changes. Material: The watch case is made of titanium, which is lightweight and skin-friendly. Model Number: The number visible on the case back is 111-11513-81M. Water Resistance: It is water-resistant up to 10 bar (100 meters). Perpetual calendar, luminous hands/numbers, sleep function, and overcharge protection.