17-637-0 SPI Micrometer Set 6-12" with CertSPI Standard Outside Mechanical Set Set includes 6 12" Measuring Range 0. 0001" Graduations Accuracy 6 7" Model: + 0. 0002" 7 8" Model: + 0. 0002" 8 9" Model: + 0. 0002" 9 10" Model: + 0. 0003" 10 11" Model: + 0. 0003" 11 12" Model: + 0. 0003" Ratchet Stop Thimble Carbide Spindle Faces 0. 25" Spindle Diameter NIST Traceable Calibration Certificate Furnished in fitted case Micrometers included in set 6 7" Outside Micrometer 7 8" Outside Micrometer with