A spacer/insert set that matches the fuel tank capacity of IF18-2 with the regulations of international races such as IFMAR. The thinnest spacer is 0.5cc, allowing you to make fine adjustments to the tank capacity by increasing or decreasing the number spacers.(1.5cc Upper&Bottom Spacer each 1pc.0.5cc Spacer 2pcs,M3x10mm/M3x12mm/M3x14mm screw each 1pc)