Screw the base of the front sight post up or down so itis even with the flat area of the front sight assembly. You can line up the line on the rear appeture with the line on the base of the rear sight, or I like to max out the rear windage knob one way or the other than count total clicks from one side to the other then divde by 2 and set it on that number. This works as a great starting point and will "Battle sight zero" most AR's. Oh I forgot set the rear elevation on 8/3's and sight in at 25-30 meters. This setting will allow a 20" AR to hit a man size target out to 300 meters without rear sight adjustment with most factory ammo.