1.KEEP VEHICLES FROM SLIDING , AVOID DANGEROUS ACCIDENTS WITH THESE CAREFULLY DESINED WHEEL CHOCK THAT FEATURES BUILT-IN TRACTION GRIPPERS TO CREATE MAXIMUM FRICTION BETWEEN THE TIRE AND THE PARKING SURFACE. 2.rECOMMENDED FOR CARS TRAILERS TRUCKS, OFF-HIGHWAY CONSTRUCTION EQUIPMENT, BUSES, JETS AND OTHER HEAVILY LOADED VEHICLES, ALSO GREAT FOR RV'S, BOAT TRAILERS AND OTHER RECREATIONAL VEHICLES. MORE KINDS OF WHEEL CHOCK PLEASE CHECK OUR WEBSITE: http:www.runbell.com