My favorite bus - Leapers UTG Top Mounted Deployable Rear Sight

I have used several different backup sights, and so far this is my favorite. Works well as a primary iron sight on AR's with flat top and FSB's. Very easy to change apertures and each aperture is perfectly sized. Much better than certain polymer sights that cost twice as much. As a side note, the area where the locking ball travels needs a little polishing. I spent five minutes smoothing that area with sandpaper and a small diamond file. It worked well before, but now it works perfectly. A little graphite (pencil lead) also helped. Don't let the small improvement I did discourage anyone from buying this sight. It a good sight straight out of the box.