Tiger Brand Jack Post JS-15 - Size Range 1&#39;-1&#39;3" (15Ga) DURABLE - Premium quality, heavy duty high carbon steel. ADJUSTABLE - Easy to assemble, easy to install. HEAVY DUTY - Corrects sagging floors, supports basement beams and stairwells, and more. SAFE - Double locked for added safety. SECONDARY SUPPORT - Can be used permanently if as a secondary support.