The plastic spinners with the plastic spinner plate shouldn't be used at all on any plane, I have seen so many of these junkers break and fly apart it scares me if I have to pit next to one of there users. I do use the nylon spinners with the metal back plate on my big planes that get hand started. I have a big box of them I picked up at an auction so I use them. These are nylon, not plastic. If I have to go out and buy a spinner I buy a good metal spinner, why fool around with anything else. I started using Magnum spinners due to the cheap price and found them to be as good as any other spinner, better then the ones sold through tower. My LHS sells them so I have no problem finding the size I need. The spinner size is dictated by the plane itself, you want the back plate to be the same size as the cowl nose.