Akron Products Adjustable Shoring Jack - 4x4 SHORING JACK - Transforms a nominal 4 x 4 lumber into an adjustable building product. NON-PRIMARY SUPPORT - Recommended as a temporary or non-primary support. HEAVY DUTY - Load capacity dependent on a 4 x 4 used up to 24,700 lbs. ADJUSTABLE - Easy to assemble, easy to install. MULTIPLE USES - Construction projects, Repairs or installations, renovations, sagging floors, and more.