`HITCH-TITE` (use on receiver Models) is a simple method to ensure a no-slop hitch attachment A size specific metal sleeve w/a nut welded to inside of it; This metal sleeve then slides into base of rack Line nut up w/ pre-drilled hole in base Customer slides base into receiver hitch & uses special threaded hitch-pin included, to tighten (Retro-Kit available) Included with all locking models, e.g. Porter Hitch 4, Cycle On Pros, and Axis Aluminum Locking Pin