Low profile beams to provide more storage space between shelves. Double rivet beams at top and bottom of unit form a rigid structure. Shelves are adjustable in 1-1/2 in increments. No nuts, bolts or shelf clips. 5-shelf system. For garage, industrial, basement, warehouse and office. 1/2 in particle board decking. 14 gauge posts. Can be assembled as a 72 in unit or two 36 in workbenches. 4000 lbs. total capacity.