These are excellent back-up sights. I've seen no change in my zero after multiple flip ups and downs. I've got the sights mounted on an AR with a DD Omega X rail. The rear sight has a portion (the windage adjustments) that go slightly below the top rail. This gives it a really nice flush look. (NOTE: this rear sight wouldn't fit right on my Sig 556 -- which has a picatinny rail all the way to the back, not like the AR.) Highly recommend. The sights are pricey -- but you get quality for what you pay.
Pros: Maintains accurate zero, even after multiple flip-ups/downs
Cons: High cost
This review was written in the old system and had content requirements that are different than reviews written today.