Our Bag Supports can used for many different application and can be used on either the front or rear rack. When we developed these, we wanted a functional, yet "Easy On- Easy Off application. The pig tail hook goes up, over and underneath the bar of the rack, they can also be used upside down on the rear rack as side boards. To install them wing them out, slide them in place and then wing them back down. Simply reverse the process to remove them. The Rok-Straps are used t keep them in place and when they are on, they are SECURE. They are pre-drilled to accept the pattern of the Roto-Pax Pack Mount (sold separately) so you can carry fuel. Attach them to your own bags or use them with our Pannier system. They are sold together in a set of one right support and one left support.