The magnetos on some of the big gas burners need to spin about 600 rpm before they will generate enough voltage to fire the spark plug. This is easy enough to do with the engine's original pull rope starter on the chain saws they were intended for but requires a serious slap on the prop of a model airplane.

Peronally, if I had such an engine and $325 to spend, I would convert that money into an electronic CDI battery powered ignition system and save the weight of the magneto flywheel instead of spending it on this starter.

Glow engines, on the other hand, are so easily hand started that I see no need to own an electric starter. Just one more battery to charge and more weight in my field box.