I use these (prop savers) rather than prop adapters. Couldn't be happier...

You have to scan down to about the middle of the page...Also, get a supply of O rings to match while you are at it. I'd think your LHS has them.

Also, after you have it fitted properly, consider cutting the excess length off of your motor shaft. Too much length will inhibit the prop from folding over..which keeps it from breaking. I went though a ton of props until I started using these, instead of adapters.
regards, Rich

http://www.ncweb.com/biz/dan/PropAdapters.html