The Killer RC™ Rear Turnbuckles for HPI Baja include two polished billet aluminum spacers, and two heat-treated alloy steel turnbuckles. These high tensile alloy steel turnbuckles are specially heat treated, giving them greater strength than titanium or stainless steel. Then when you add the aluminum spacers you have a setup that is many times tougher than the stock setup. The aluminum spacers simply work by spreading out the forces to a larger area on the end of the arm and ball end. Installation is easy. Just screw the turnbuckle into the arm, slide the spacer over the turnbuckle and tighten the ball end tight up against it. You should not be able to move or spin the spacer. The aluminum spacers will fit overtop of PhatDad turnbuckles. They will also fit overtop of Fast Eddy pro turnbuckles if you drill open the spacers' a little bit. For spacer length choose 12mm (stock camber), 9.5mm, or 14.8mm spacers (great for the FLM extended arm kit).