Recently purchased a set of MI back up iron sights from big daddy unlimited. Went to put them on my rifle and tighten down the mounting screw and the screw head broke in half. Needless to say I was pretty pissed. Paid $100 for the set. Called up the company and they were aware of the problem. Said they would send me out a new set of screws. Said they had a batch that were over hardened. Figured they would take a week to come in but only took two days. They also threw in a couple nice hats and several stickers. If you need a set of sights I wouldn’t look pst these, even with the problem I had. Quality set and quality customer service.