RUMBER® LIFETIME RECYCLED RUBBER WHEEL CHOCK HIGHLY DURABLE & ENVIRONMENTALLY FRIENDLY MATERIAL!! BY BLENDING RECYCLED TIRES AND PLASTICS IN AN EXCLUSIVE PATENTED PROCESS, THESE SOLID RUBBER WHEEL CHOCKS ARE A STRONG AND COST-EFFECTIVE SOLUTION FOR CHOCKING TRUCKS, TRAILERS AND OTHER EQUIPMENT. CHOCK IS CONSTRUCTED OF 100% RECYCLED MATERIAL THAT IS IMPERVIOUS TO FLUIDS, MUD, OIL AND ULTRAVIOLET RAYS. BUILT-IN TRACTION GRIPS OFFER MAXIMUM FRICTION. MEETS OSHA REQUIREMENT 1910.178(K)(1) TO PREVENT MOVEMENT OF TRUCKS OR TRAILERS WHILE LOADING OR UNLOADING. RECOMMENDED TO BE USED IN PAIRS.