I ordered this part and added it not to F103RM chassis, but to my F103GT chassis. It works perfectly, even my LiPol battery was very big for it, finally it was assembled OK. Very interesting part, because its dramaticly change the grip.
Probably the best upgrade for f103 chassis. it definately improves the handling of the car. rear wheels now have much better grip on the track. if you consider upgrading your f103, this should be among the first few things along with the flexible T-bar set and oil damper.