I've bought 6 or 8 (I've honestly lost track at this point) or so of these and used them to mount electric guitars, electric bass guitars, acoustic guitars and other items to the walls of my apartment and studio over the past year.
They are very easy to mount, works with pretty much any instrument and are very reliable.
I put a 10 pound sledgehammer on one and left it there for a month or two, just to test if it could take it and had no issues.
I did have problems mounting my banjo and my electric violin on it though, so if you intend to mount instruments with a very narrow neck this may not suit you.