These Arms Are Used In Conjunction With The Re4020 Arms To Convert The Factory Four Link To A Radius Arm Design. This Change Improves Ride, Handling, And Driveline Geometry In Your Lifted Jeep. This Arm Is Constructed Out Of 2" X 1/4" Wall 4130 Chromoly And Is Nearly Bulletproof. The Arms Are Adjustable And Feature Our Super-Flex Joints For Increased Axle Articulation.