OS Power backplate improves efficiency of the engine adding power and mileage using special air ports in the backplate to channel crankcase air fuel mixture.
 
Fits OS Based ( BLOK, Protek, OS, Maxima, Bullit, etc...) including the OS .28 engine as well as ALPHA RC engines  and some, NOVA and  Novarossi .21 engines that use a  26mm diameter backplate and 14.5mm depth.. Comes with O-Ring.
 
Please measure before you order to make sure it fits your model.
 
More POWER, more RPM and Better tuning! A must have for the serious RC racers who wants MAX power from there engine!
 
** Always check before starting the engine that when the backplate is installed is spins freely with no interference.there are so many models of these  engines and they may make small changes in specifications to the engines at times during production without notice.  So always check fitment before strating engine. BUyer responsibility to check before using.**