Przise gearbeitet - guter Rundlauf - empfehlenswertIt works well, but there are no grooves to grip the prop and the grub screws are very small for the size of adapter, so I'll give it 4 stars. It is well centered. About 22mm diameter, 45mm long.These work very well. I used to use the collet type to try to avoid scratching the motor shaft, but sometimes had problems getting them off the shaft after they'd been tightened up. Especially in my planes with a cowl. The only improvements I'd like are larger grub screws and harder aluminum, especially on the smaller size prop adapters, where it is too easy to strip the aluminum threads. That is not a problem with this prop adapter however. The 8mm prop shaft is more than strong enough, and the threads are course.