I bought this together with the "5417BLK Rack Screws" from Adam Hall to mount gear in my rack and it's what you expect. It's of nice quality and fits easily in square rack holes. Sometimes it's a bit hard to get them in, but this applies to every cage nut.
It sits perfectly in place and holds my gear where it should be. It also has enough space to move a bit in the holes.
It's the perfect choice for rack mounting in my opinion. Buy this and the earlier mentioned Rack Screws and you won't be disappointed!