The 88-8 Premium extra heavy duty wheel chock is made from recycled laminated rubber pads assembled on 3/4" bolts and compressed between 1/4" steel plates. The 88-8 Wheel Chock is contoured to fit tires. Fully meets OSHA requirements Guaranteed to be free of defects in material and workmanship under normal conditions of usage, provided our recommended installation and maintenance instructions are followed.