Designed expressly for the F3C & 3D competition. Improved hovering stability as well as power at high speed to meet the further sophisticated F3C competition manouevres New design piston and crankshaft reduces vibration to provide further, stable torque over the entire RPM range. The rectangular heatsink head is completely included in the cooling shroud for better cooling in a fully enclosed body. Black alumite finish with O.S. and 91HZ logos impart a distinctive image. Integral back plate heatsink improves crankcase cooling. A Thermo insulator is installed on the carburetor mounting spigot helps shut out engine heat to the carburettor, which in turn ensures a stable fuel/air mixture. Needle Control Lever with O.S. Engines logo is supplied with the engine as standard for the CSM carbsmart.