The Shaft Optimizer was used during my fitting. It spit out some suggestions and we went from there. Built some clubs and let the numbers do the talking from there. I went in using KBS Tour S and left with PX 6.0. Suggested were KBS C-Taper S, DG S300, and PX 6.0. It wasn't really anything groundbreaking for me but I could see where it could be for someone that has no clue about equipment or their swing dynamics.