These are Slash 4x4 left and right rear RPM A-arm rock shields. They protect leading edge of RPM aarms, drive shafts and carrier from flying rock spray by front tires with brushless motors. Clearance to shocks is tight, no problem with traxxas stock and big bore shocks but don't know about GTR shocks or others. Gravel and rocks spray really pound everything back there, this really helps save your fancy aluminum carriers and driveshafts. Build with support. Some fileing and cleaning to make fit. Use shock holes to mount shield with 3m bolts. UPDATE, just downloaded some upgraded shield that hold up better. The first ones I broke a few. These seem to be holding up, have not broke one yet. Really saving my 50 dollar rear drive shafts from rock spray.