Like the RailLight Premium, its solar-powered so you never have batteries to replace. A built-in sensor turns it on at dusk and two white LEDs deliver up to eight hours of light on an eight-hour charge of sunlight. Included is the QuickMount rail clamp so you can quickly attach or detach it from any railing up to 1 1/4" in diameter. Built to last with marine-grade stainless steel, UV-proof lens, and sealed electronics. Single 1400mAh rechargeable and replaceable NiMH battery included. 2 3/8"dia. x 11"H. One-year warranty.