EACH LEVEL REQUIRES FOUR BEAMS. USE DOUBLE RIVET BEAMS ON TOP AND BOTTOM LEVELS OF ALL UNITS. USE SINGLE RIVET BEAMS ON ALL INTERMEDIATE LEVELS, OR INCREASE CAPACITY BY USING DOUBLE RIVET BEAMS ON ALL LEVELS. BEAMS CAN BE USED AS LEDGES AT ANY REQUIRED HEIGHT TO PREVENT MERCHANDISE FROM FALLING OR ROLLING OFF SHELVES.