78XTZ-312 Bore Gage 68129

78, 78M Inside Micrometers, Extended Travel with Setting Rings and Cases
Inside Bore Gage Micrometer, 1/4-5/16", .00025"

The Starrett 78XT Series Internal Micrometer features extended travel, reducing the need to exchange anvils. The ground contact points seat the internal micrometer faster and more accurately than the spherical contacts found in other gages. The rugged and accurate internal micrometer is available individually or in economical sets from .040-12" (1-300mm). 1/4-5/16"-¥ Range, w/3 Point Carbide Contact.

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  • Wide measurement range without changing anvils
  • Tungsten carbide measuring faces on all 3-point heads above 1/2" (12.5mm)
  • Ratchet stop ensures consistent measurements
  • Self-centering contacts for true readings
  • Blind bore measuring capability above 1/2" (12.5mm) diameter
  • Extensions available up to 6" (150mm) for deep hole measuring
  • Setting rings included
  • Depth stop/collar also available for .080"-.250" (1-6mm) range
  • Each micrometer bore gage is furnished in a case, complete with setting ring, contacts, wrenches, and instructions


  • Made in America: No
  • Range (in): 1/4 to 5/16"
  • Graduations (in): .00025"
  • Approximate Measuring Depth (in): 2-1/4"

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