I have the Williams peep on my Knight and love it!
My muzzy zero is at 200 yards, center of fiber optic. At 100 yards the point of impact is at the top of the front fiber optic.
I have the small insert in the peep, when it is too dark, I unscrew it and use the large hole as a ghost ring (how I shot my elk this year...too dark to see in the timber)