Glass Scale: MicroRule 25" .002"/.05mm This glass scale provides both English and Metric patterns that are formed by a very durable, double layer of chrome deposited on select .220"/5.6mm thick soda lime glass. The glass is fully supported by low reflection extruded aluminum side rails with end caps to retain the magnifiers and protect the glass during shop use. Dimensions and tolerances of each MicroRule are: Scale division of 0.002”/0.05mm 25” pattern length and an overall length of 27.85” Line to line accuracy of ±0.0001” Overall accuracy of ±0.0003” Each MicroRule includes: Two (2) 12X magnifiers Carrying case for protection during storage In addition to the standard “Certificate of Accuracy”, any MicroRule can be individually calibrated to provide “Certified Calibration” Traceable to N.I.S.T. Click here to download drawing