This is used in conjunction with Condor's adaptor kits (TK-3000 & SC-2000) by simply bolting the TK-2601 under your trailer kit (on the underside of your trailer) so that you are able to reinforce the trailer adaptor assembly, if necessary. The Pit-Stop Chock Trailer Adaptor Kit (part#TK-3000) requires only one TK-2601. The Trailer Kit for the SC2000 chock (Part# SC-3000) requires two TK-2601.