I bought a set of Pro Mag BUIS for my first AR. I didn't know much about anything AR at the time. Shortly after I learned that the Pro Mag AR mags were not Pmags, and started to question the quality of my flip ups made by them. This was three years ago. Never had an issue with them until three weeks ago. I let my friend shoot the rifle and after he emptied the mag, he turned to walk toward me and I saw something fall to the ground. It was the rear sight. I couldn't believe it. It was like it exploded, but nothing comes anywhere near contacting it. I'm sure they have some sort of warranty, but it would drive me crazy worrying about the quality, since your buis are what you depend on working when all else fails. Big deal for a range gun? Probably not, but I will be buying Troy or MI next time.