OPTIONAL SECURITY CHAIN FOR DURABLE WHEEL CHOCK HANGER OPTIONAL SECURITY CHAIN HELPS PREVENT CHOCKS FROM BEING STOLEN. 10′ LONG CHAIN INCLUDES 1″ X 1″ ANGLE IRON MOUNTING BRACKET FOR MOUNTING TO THE DOCK WALL. OSHA REQUIREMENT 1910.178(K)(1) STATES “THE BRAKES OF HIGHWAY TRUCKS SHALL BE SET AND WHEEL CHOCKS PLACED UNDER THE REAR WHEELS TO PREVENT THE TRUCKS FROM ROLLING WHILE THEY ARE BOARDED WITH POWERED INDUSTRIAL TRUCKS”.