This 30mm EDF case is designed for speed set ups. The 4 stator vane configuration allows a 3 blade rotor to work at maximum efficiency. The motor mount is designed for 12mm inrunners. The mounting holes allow for 1.6M screws (and larger). The front flange increases intake air flow efficiency. Use this case even if you are mounting in a duct setup to allow +100% FSA air flow.