Precision diameter tapes are manufactured to exacting standards in temperature controlled facilities at 68F (20C). The lines and numerals on our standard tapes are engraved and acid etched on a ground surface. The tapes have fixed readings that do not require periodic adjustments. Pi Tape Corporation's 1095 spring steel diameter measuring tapes are delivered with a Calibration Report traceable to the National Institute of Standards and Technology. Spring Steel tapes are suitable for use with all materials and in non-corrosive environments.Standard Inch tapes read to 0.001 diameter with an accuracy of 0.001 up to 144 inches.