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Dimensional lumber tape measure
(slrpnk.net)
I hope it’s not against the rules here, just saw this woodworking related xkcd that I enjoyed and thought it might be appreciated here:)
They are cut to within 1/8th inch at best, and 1/4 was more likely. I was in construction for a while and this is what we did. Wood is not suitable for higher tolerance work: humidity and temperature change dimensions significantly, if you want something more accurate you need to use metals.