Review on Empire 3990 12 Inch Heavy Duty Magnum by Gary Shakeone

The extended side of the square is 0.005 from a straight line compared to the Starret ruler. The .005 gauge probe enters 3 1/2 inches to the end at a 90 degree angle and 5 inches from the other end against the indicated edge. Result: When checked from the side at 90 degrees to the inside of the driver's 5x9 square, the error is 0.015. I plan on rubbing it on the surface of the slab until it's straight when I have time. If you use it full length to test an internal 90° angle, it's ok because it's full length. The price for it was very low, so it's not worth returning. I'll be happier fixing this. Right, I recently corrected the smaller machinist square that wasn't the correct 90 degrees