If I could sum up this product, it would be "the harbor freight of gun sights". Everyone knows that harbor freight has a bunch of garbage that's not worth buying at all, some stuff that works well after you put time in to tweaking it, and very few items that just work great. These sights fall in to the "work with some tweaking"...possibly.The good-they are solid aluminum. I assume 6061 since it filed down very easily. The rotating knob for windage on the rear sight has a great tactile feel to it with solid detents and the aperture does not wiggle, its locked no matter where you adjust it to.The bad-like almost everyone else, I had trouble securing the front and rear sights to my rail. There was wobble at first but it cinched down after backing in and out a few times. While it is tight, it is at the very edge of being so. There should be more adjustability with this. I'm going to blue loctite the bolts once finally mounted along with safety wire in case it doesn't hold. We use lock wire with all of our sensitive items on firearms at work so we dont lose our red dots, peq-15's etc. Just some peace of mind. The push buttons to flip the sights are nice and stiff so as to not accidentally deploy. Unfortunately the buttons are also very "grindy". The button is actually a bolt that goes all the way through the unit and the shaft and/or the tunnel it goes through is not finished well. This will eventually cause movement as its abrading the surfaces in there and will cause misalignment if the sights are used often. I dont plan on ever using them unless my red dots fail I need them in a pinch.The rear sight has a cutout to clear the spent casing deflector...it doesn't clear it. As you can see in the pic I did some quick filing of a little portion with my Gerber and its good to go. Also with the rear sight, the apertures I thought were well sized for me, but I'm going to lightly sand both holes to take the gloss off. It has a sheen to it that screws up sighting due to reflections..not a big dealThe ugly-both sights had a good amount of slop from side to side due to the gap between the base and the flip up portion. I didn't measure this gap at all. But the movement was not acceptable for combat situations. It would never hold the same spot after flipping or probably firing as well. I ended up taking the units apart and inserting a washer to take up the space. I sanded both washers down and test fitted them until they made the unit snug. When reinstalling the push button, I put blue loctite in the oval end "nut" to keep it all together. Not fun and very time consuming.Now the worst part. This may also make the sight completely unusable and all my time in these put to waste. The front sight post...it MOVES about .5 mm off center with the slight push of my finger. This is due to the threads not being cut perfectly. While it was a cheap buy-this is not where to cheap out with sights since the front sight post is the ONLY way to adjust elevation. The rear sight only has windage adjustments. So how to fix this? I'm not sure the method I'm going to try will work, but I'll edit this post to give the results. I plan on first taking the front sight post completely out and wrapping it generously with teflon tape and the reinstalling. I'll then test the movement as well as if it is even centered. If it looks good then I'll zero while checking after each shot if the post held its position. If this does not work I'll move to method 2.Method 2 with be removing all of the teflon tape and reassembling the unit to zero as it came from the factory. Again, I'll make sure to move the sight post back to center after every shot. Once(if) I've zeroed, I'll keep everything as is and flow some red loctite in to the threads.If neither of these methods work the only thing left is to rethread the base unit with an insert...and I'm not doing that.So this is why I call it the"Harbor Freight" of backup sights. A lot of work to make it work, only to hope that it works.I'll post results once i get the rest of my optics and bore sight laser for the most accurate results