For raising walls, beams, or to tighten and true flooring; Easy to use; Economical and portable; Constructed of heavy duty malleable iron castings; Designed for use with 1-1/2" x 3-1/2" (2x4) fir poles; Capacity: When used in conjunction with poles made of clear straight grained fir wood, free from all knots or defects, the wall jack has a capacity of 1000 lbs.