I made an AR 9mm SBR with a1 upper and had a clamp on front sight that didn't work out well for me, but I'd gotten one of these as a possible replacement so slipped it on yesterday...
Well, slipped it on is a bit of a misnomer. My barrel measures .750 and I had to spread the base a little to even get it started. It's so tight it made marks on the finish. Nothing serious, but just to illustrate how tight this thing really is. I'm not worried about some longer sight radius, but I wanted an iron sight on the gun that didn't need a gas tube or the associated length required for one.
All in all, I like the sight a lot. I'm not a fan of the AKstyle sight post being used, but once I set it, it won't matter in the long run I'd think.
It's very well made, but cost wise seems a bit higher than I'd like, especially with the ak-sight simplicity, but obviously it's not a deal breaker since I bought it. :)
Picture of the SBR: