RPM extended rear A-arms are designed around their already solid and proven Revo rear A-arm design. That means you get an ultra lightweight set of A-arms that are nearly indestructible! Each set of RPM extended rear A-arms incorporates all stock geometry including options for either a 10mm or 19mm extension. Tech Notes: RPM Extended Rear A-arms are replacements for TRA stock #5333R. 6mm bumper mount spacers (not included) and M3 x 16mm screws (not included) may be necessary if installing these in place of standard wheelbase a-arms.