I use a keller and have for years. Pretty easy to use. Sight it in from the ground at 20 yards locked in the number 4 spot to get your left/right adjustments made, then unlock the pendulum and shoot from an elevated spot 12 feet or higher at a target set 12-15 yards out. Make adjustments up or down based on this. Very simple to use and has been very accurate for me. I strictly bowhunt out of tree stands so it fits what i need.