Kinex 4001-03-075 Machinist Knife Edge Solid Inspection Square 3 x 2 x .225 Inches Thick (75 mm x 50 mm) DIN 875/00 (Square w/in 3 microns or 0.0001 Inches)

Great little square. Love the knife edge, makes string alignments a breeze. Worth mentioning that it’s also magnetic, and in combination with a little pocket level (I recommend a starrett 135A for around 30$) and a few craft magnets, quick plumb level checks can be done in less than a minute. 5 stars, great product.

This item maybe defective, I’m skeptical since I don’t have the instruments to be sure. I checked it against 4 different 1-2-3 blocks, a din-0 square and woodpecker delve square - in all of them there is a gap at the same location :-( I’m returning this item.

Fantastic Square, Thinking of ordering all sizes.