One of the reasons I love teaching instructor classes is I get to spend time with very knowledgeable professionals and share knowledge with them. I generally learn as much from them as they learn from me. This Glock Sight is an example of this.
In one my Pistol Instructor Class, I noticed one of my students had marked a small dot in the middle of their Glock rear sight.
We discussed what he did and why, and I spent some time playing with it, and I felt it was something useful to share.
By the way, if you are in Northern Mississippi and are looking for a very smart firearm instructor, let me know and I will pass you info on to him.
Anyway, by taking a fine tipped sharpie and placing a line, dot, or diamond in the exact center of white line in the glock rear sight it can help those of use with older eyes line up the front and rear sight.
The only caveat I can think of is that you need to ensure it is exactly centered on the rear sight.
Try it, and tell me what you think.