I recently put a set of the "UnderTaker Turkey Sight Kit by Hunter's Specialties" on my boys Mossberg. Looks to be a decent set up. Rear sight attaches with 4 screws to a plate that is cut to fit against the bottom of the rib. Front sight mounts with a screw in the front sight post hole.
I like the looks of them. Except the ones i have the rear sight is plastic. I am afraid if not careful it will get broke. I figured for $8 I would try them. We have not shot with them as of yet, maybe today to see if they are worth it. If I do, I will post up the results.
I would like to find a regular style peep site, made of metal. Just have not found them affordable yet.
Lonny