They are great they are very strong and thick enough to clamp at any angle. The only downside is that they have a notch on the outside corner. So if you draw a straight line around the edge, the line won't be perfectly straight. I'm sure they do it for a reason. I'm sure it's a feature I don't know about, but trying to draw a straight line at a 90Β° angle is just a pain in the ass. to replace it with a ruler for the last half inch of your line.