Unique Quick lift by power drill, save huge amount of time by traditional hand winding Great for providing support and stablize to RV slide outs when extended Capacity: 5,000 lbs per jack, included 2 jacks,one crank handle, one 3/4" socket, Powder/zinc coated to prevent rusting, top support plate dimention: 5-1/8" x 3" Adjust from 21"-37" on height quickly and easily by power drill or hand crank handle 3 sizes (by different listings) to choose, better stability than universal one-for-all jacks on market! U-bracket size: 5.8"x3", Foot plate dia: 5". For RV slide-out part stabilizing and supporting purpose only, NEVER use for lifting, changing tires or supporting weight of any vehicles,