Crankshaft stop (piston stop)

"You can twist this pistonstop or blockpin in your spark plug hole. That will block your piston, so the crankshaft will be blocked and you can pull your vario and flywheel. This is easy and clever tool, but use it wisely because if you use too much force you can destroy your piston. Fits in all standard screw-wiring (M14), so not in Injection and 4Takt engines."