"Tow Tuff introduces the Tandem Wheel Chock Pair. This chock pair is uniquely designed with scissor-action technology to prevent the rolling and rocking of your tandem wheel trailers and campers. The wheel chocks extend form 1.5"" to 5.5"" to provide the stabilization that you need for your tandem wheel trailers and your campers. The one-step lever action is easy to use and the chocks will even prevent movement when unhooking your trailer/camper as they securely lock your trailer/camper into place."