Holy crap-I’m gonna get one! Thank you for posting that!
I looked for a video to see how this worked because I’m a visual person and don’t get it and found this little video that might help someone; maybe even me since my eyesight is progressively getting worse.
https://www.youtube.com/watch?v=-6a20stHk6k
A cheap, or even free method if you have the clip-on laying around, of getting that sight picture focused in.
No problem! There’s another one I forgot about - http://seebettershootbetter.com/Magnetic%20Shooting%20Aperture.pdf