The reason to own one is cutting rather than measuring. A craft knife run along plastic or timber shaves the edge on the first pass and every line after that is wrong, where steel takes it indefinitely. A cork or rubber backing stops the rule sliding and lifts it clear of wet ink. Check the markings are etched rather than printed, since printed scales wear off. See plastic rulers, cutting knives and rulers.

Stainless steel ruler arranged with technical drawings, pencils and stationery on a bright light timber desk.
Metal Rulers for Measuring

Shop metal rulers for measuring, drawing, craft, cutting guides, school work and office stationery.