a modifiable rack system can be connected to a vehicle such as a truck or a tractor , and includes a receptacle for holding a variety of items including materials and equipment . the rack system includes a variety of add - ons for organizing and retaining equipment , and a hinged tail gate for easy access . the rack system includes a trailer hitch so a rolling trailer , or the like , can be daisy - chained off the back end . wheels can be mounted to the rack system so the rack system can used as a rolling cart . the rack system is able to withstand large forces during use because of a tow support spine , and associated structures , which impart tremendous strength .