Im with TeeJay on this one I dont want to have to worry about a geometry lesson to try to figure out where to aim. With the penedulum just put the pin where it goes and let her rip. I have shot over too many deer in the past. I have not missed one since I put the penedulum on. You can always buy one of the new Leupold rangefinders that have a built in level in them. They tell you how far the animal is and what the angle is and what the distance you have to aim at.