Wesco 230052 Aluminum StairKing Battery Powered Stair Climbing Appliance Truck with Auto Rewind Ratchet, Moldon Rubber Wheels, 850 lbs Load Capacity, 24" Width x 72" Height x 12" Depth Welded aluminum construction 1/2 Horsepower, 50 ampere, high torque motor runs cooler under load Industrial grade gear box transmits steady power and is preferable to other drive designs Large 2-inches diameter, polyurethane lifting feet provide more secure stair gripping Auto rewind ratchet works first to take the slack out of the cargo belt and then provides a ratchet crank to securely tighten the load