You want to see two images. If you close one eye, in my case the left eye, the target disappears. However, with the focus on both, the front sight seems to be translucent, but clearly in focus. Now, instead of using the flat square top of the sight, you can use the white dot as an index point. If you can't see the target, you can't index the front sight. (fine precision shooting)Usual shooting distances vary from arms length to 50 yards.