The RCR A-Arm bushing kit is made up of the highest materials available on the market today. The bushings are Made from machined Delrin with a gun barrel rifling for 100% grease distribution. They are made to last for years versus the cheap plastic oem bushings. The sleeves are made form 4130 Chromoly steel and have a grease groove in the end to trap dirt and debris from entering the bushing and keeping the bushing lubricated. .