S.F.S.-
I can't figure out how to post a pic, but both are basically a full circle that you look through, while positioning the front sight in the middle of the circle. A "peep" sight has a smaller hole for a finer sight picture, while the hole on the "ghost ring" is larger for faster acquisition. On the latter, while focusing on the front sight, the aperture will almost completly blur out of focus. Hence the term "ghost ring."
Denny
