Its for bullet drop. Ill try to get it out and get a better pic of it tomorrow its a bitch to do though because i dont ahve a bench rest for it. You zero the tip at 100 yards and for each 100 you get out beyond that there is a dot. The very bottom is like 19 inches at 300 yards so you center up your target and squeeze it off. Its made so you never have to adjust it once zeroed