I was building a set of drawers and wanted the drawers to be perfectly straight. When I received my order (8 of them) I checked them with a square ruler and one or two might just be a little off. I couldn't tell exactly because it was such a small difference, but I decided to keep them anyway. I'm glad I did because they are great. There are small design features that are not immediately apparent. Things like this work great with different widths of wood, can be used on a joist, etc. They worked great and my project turned out exactly how I wanted it. I love these things now and use them all the time. It's almost impossible not to have good right angles when you push them in.