Do you add your own ring. That is the style that I was thinking about. I see these are fixed dots. They should be centered but have never trusted one to be so. If you rotate the lens 90 or 180 degrees etc you will change your aiming point. You can adjust the sight a click or 2. :) I am always careful to set the lens in the same way. I have had sights with notches so they can't be rotated.
With my target panic 1/4 inch at 20 yards is the least of my worries at the moment!