I use a TruTurn 2.5" spinner with the 120 slots and that suits just about any prop you'll use on the skybolt.

The spinner supplied with the skybolt is decent but the slots were too small for 4-stroke sized props and i hate grinding spinner so elected for an aftermarket spinner.

I used the adapter finder on TruTurn's website to find the right spinner nut. Off memory it's part # TT-0828-A but you should check first.

http://www.truturn.com