With a Powered Stair-Climbing Dolly (also called hand truck), a single individual can transport many types of heavy objects up and down stairs, on and off delivery vehicles or loading docks, and into and out of buildings. Most makes/models, which run off a battery-fed 12-volt motor, are fitted with a second set of wheels that, when push-button activated, extends out from the frame and engages the next step up (when climbing) or next step down (when descending). Again, depending on make/model, the dolly's lifting capacity, lift height, strapping system, braking system, handle type, nose-plate dimensions, etc., determine price.