Well you have to take what I say with a grain of salt (I am the US importer of the OKO sight), but here goes....
I first bought the OKO at shot-show 99' as a dealer sample and used it on my personnel rifle for almost a full year before I decided to sell the sights. The one-pictured below is on my full auto 9mm (this is also the gun I let the cops play with). You will notice that there is no steel cover on it. I have had this rifle hit the deck several times and I don't use a hard case. The point of impact has not change in the 4 months of [b]heavy[/b] use. The OKO sight is simple to mount, easy to use and in my opinion very rugged and reliable. You can get them From Castle Arms (Tim and John from right here on AR15.com), DPMS, Dillon and Brownells. I know some of these companies have a no questions asked return policy, so how can you loose?
[img]http://www.cavalryarms.com/sn_9mm05.jpg[/img]
[img]http://www.cavalryarms.com/oko_chm_02.jpg[/img]