Review on Precision Stainless Steel Metric Millimeter Machinist by Brian Garrett

These are called "machinist rulers" and must start at zero so you can measure from the end. However, none of the four rules in my set were followed exactly: the ends were 0.3 mm or 0.012 inches (more than half the smallest pitch) from zero. , checked the alignment under a magnifying glass and grinded it down to 0.002" from the correct reading on the inch side. However, the millimeter graduations engraved on the other side of each ruler were not necessarily of the same origin, and the worst differed by 0.3mm. The photo-engraved graduations themselves are accurate, but the mechanic's ruler must also have an accurate origin. , but these are not. Their main advantage is a very low price. If you want a finely ground, real machinist's ruler, the PEC Tools ruler is probably the most affordable option.