I been meaning to talk about this for a while but kept forgetting. Unertl optics is known for their high quality external adjustment rifle scopes. Most people who have heard the name Unertl, don’t know they also made iron sight.
The tube sight even looks like an optics from a distance. The tube has an adjustable rear peep that is adjustable by the user to size they want. Windage and elevation is adjusted the same was as the optics. Even mounting on the same target blocks.
It’s simple one long rear sight. A front sight was still needed of course.