Straightarrow, thanks for the link. Wish I saw it earlier, would have saved some typing and it explains it better . Have you tried 450 Plus? If so how do you like it compared to the Brownells? I started with S4 but didn' t like it so have been a 450 Premium then Plus user and had no complaints. Have 8125 on the bow now but can' t see a difference between that and 450 Plus (or maybe I' m just set in my ways).