Most shooters like the lower 1/3 setup because it gives a more unobstructed view when you're shooting "heads up" and looking at the dot over the top of the rear sight. If for some reason the dot fails or you just want to use the irons, simply drop your heat or tighten up the cheek weld and you can now use the irons or see the dot on top of the front post in the lower third of the optic tube.