Increase power to dominate the competition. Multiple heights to develop reaction time and overall explosiveness. Basic drills include forward and lateral jumps. Made of fully welded 14-gauge 1 steel. Tops are reinforced 3/4" plywood with non-slip surface. Stackable for easy storage. Use indoors or outdoors. Color: Red and Black. Starter Set - 1 ea 12", 18", 24" and 30" Plyoboxes Advanced Set - 1 ea 12", 18", 24", 30", 36" and 42" Plyoboxes