📏 4 Inch Precision Machinist Engineer Square: Ground Hardened Steel, 90 Degree Right Angle Ruler with Seat, 4 x 2.8 Inch Review

Not very good. If you check it on the surface of the board, it's a bit off, but if you draw on it with a pen, hole punch, or anything else. This is where you lose precision, not the tool itself.

The workmanship is very poor: all edges are sharp, scratches and some grinding marks on one of the edges, the screw holes at the bottom are not round. People have mentioned that it's about 1/32 of an inch off, which might not sound like a bad thing, but it's only more than 3 inches.

I'm a carpenter and need a square that doesn't take up much space but has some weight; Something that will stay where I put it when I use it as a vertical drilling reference with a spacer and a chisel. It does, but it's also replaced my little combo square for a lot of things since the base is so wide. Highly recommended.