The TT-0717A is the double jam nut adapter for the Saito 91. Unfortunately, it requires boring out the prop. I was able to find a 1/2" drill bit with a smaller diameter tip at my LHS and it turned out to be pretty easy to do. After getting the drill press set up for the right depth, etc. I drilled all the props I had for this engine. Then I had to ream and balance them all. But it gave me something to do on a rainy day.