Fitness classic in a full range of sizes! Plyometric boxesáfrom Power Systems are designed to provide maximum stability and durability during your workout. Our plyo boxes are constructed of fully welded steel frames, and the tops are made from reinforced ╛" plywood with a non-slip surface to maximize safety. Black/black. Specific dimensions below. Starter and Advanced kits available. 5-year limited warranty. Use indoor/outdoor.