Enclosed sides and back keep equipment and supplies from falling off Starter units can be used individually or combined with add-on units to complete a row of shelving 22-gauge shelves are fully welded and lapped in two places for extra strength Shelves are supported by 13-gauge compression clips instead of bolts Shelves adjust in 1" increments and are 1"H to accommodate most label holders Upright posts feature a square hole every third hole for easy shelf alignment