The main advantage the Roll Design arms have over the other a arm makers is the ball joint design and the use of needle bearings instead of bushings for the lower mounts. The caster on the Roll arms is adjusted with the heim joints on the upper arms not spacers. The tie rods are stainless steel and the heim joints on the upper joints are top quality. I was lucky enough to get a pair used for far less than what they cost new. Not sure I would pay the price for new one's but they are nice!