BMW F30 F31 Brackets F Series M Sport Blue Rear Brakes 345mm-370mm M3 M4 Discs. These are custom brackets that allow you to fit full fat M2/M3/M4 rear discs on your F3 car if you are already running M-SPort Brake Package/Performance Brakes 345mm. NOTE – These require grinding of the caliper and the wheel carrier to fit. NOTE – Only fit vehicles with 185mm handbrake assembly. Any information needed please contact me.