I'm using the Predator IV this year. While it requires a bit more adjustment than other pendulums it really is an accurate sight once setup. Personally I think I would have prefered the Keller but until they make a fiber optic site available I'll stick with the Predator. And that is what the pendulum does, it's an automatic range finder. I know some will say that with todays bows you only need one pin, but for me hunting the thick stuff where the angles are steep, I need pinpoint accuracy and there is the occassional longer shot, I really require more accuracy than what is given me with one pin. The pendulum does that for me.