Yeah, I'm definitely a gearhead, always looking for some new toy to bolt onto a rifle. I'm REALLY happy with the Krebs Rail on the SGL-21, the M16A2 style peep sight at the rear of the rail is simply tremendous. I shot a ragged one hole group at 100 yds after zeroing the sights, with cheap yugo brass cased surplus. Couldn't be happier with the sights now, and it makes for a rock solid attachment point for an optic. Now, I just need to figure out which one I want...