{"product_id":"spi-21-912-1-mechanical-hole-micrometer-2-5-3-0-in","title":"Spi 21-912-1 Mechanical Hole Micrometer 2.5-3.0 in","description":"\u003ch3\u003eProduct Description\u003c\/h3\u003e\n\u003cp\u003eThe SPI 21-912-1 is a mechanical hole micrometer designed for precision internal bore measurement in the 2.5 to 3.0 inch range. It delivers 0.0002 inch graduation and 0.0002 inch accuracy, making it a reliable tool for checking bore diameters to tight tolerances. Three self-centering contact points ensure consistent alignment within the bore, while carbide measuring surfaces resist wear over repeated use. A ratchet stop thimble controls applied measuring force for repeatable readings. The instrument ships calibrated with a NIST traceability certification included, satisfying quality system requirements on the shop floor or in the field.\u003c\/p\u003e\n\u003cp\u003eThis hole micrometer is suited for machining, metrology, and maintenance applications where internal bore dimensions must be verified against engineering tolerances. Typical use cases include checking cylinder bores, housing bores, and large-diameter fitted holes in industrial equipment. It is appropriate for use by machinists, quality technicians, and precision maintenance trades working in manufacturing, heavy equipment service, and toolroom environments. The included 2.5 inch setting ring allows the instrument to be set to a known reference before measurement.\u003c\/p\u003e\n\u003ch4\u003eKey Features\u003c\/h4\u003e\n\u003cul\u003e\n  \u003cli\u003eMeasurement range: 2.5 to 3.0 inches with 0.0002 inch graduation\u003c\/li\u003e\n  \u003cli\u003eAccuracy: 0.0002 inches across the full measurement range\u003c\/li\u003e\n  \u003cli\u003eThree self-centering contact points for consistent bore alignment\u003c\/li\u003e\n  \u003cli\u003eCarbide measuring surfaces for extended service life\u003c\/li\u003e\n  \u003cli\u003eRatchet stop thimble provides controlled, repeatable measuring force\u003c\/li\u003e\n  \u003cli\u003eShips calibrated with NIST traceability certification included\u003c\/li\u003e\n  \u003cli\u003eIncludes one extension rod and one 2.5 inch setting ring\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch4\u003eCompatibility\u003c\/h4\u003e\n\u003cp\u003eDesigned as a general-purpose mechanical hole micrometer for internal bore measurement applications in the 2.5 to 3.0 inch range. Suitable for use wherever a calibrated inside micrometer with NIST traceable certification is required.\u003c\/p\u003e\n\u003ch4\u003eInstallation Notes\u003c\/h4\u003e\n\u003cp\u003eThis instrument is a precision measuring tool, not a component that is installed in a system. Handle with care to avoid dropping or striking the measuring anvils or thimble. Store in the provided case when not in use to protect the chrome finish and carbide contact points. Zero the micrometer against the included setting ring before each measurement session to confirm calibration status.\u003c\/p\u003e\n\u003ch4\u003eTechnical Specifications\u003c\/h4\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMicrometer Type\u003c\/strong\u003e: Hole\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMeasurement Range\u003c\/strong\u003e: 2.5 to 3.0 inches\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eGraduation\u003c\/strong\u003e: 0.0002 inches\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eAccuracy\u003c\/strong\u003e: 0.0002 inches\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eThimble Type\u003c\/strong\u003e: Ratchet Stop\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eNumber of Contact Points\u003c\/strong\u003e: 3\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eRod Diameter\u003c\/strong\u003e: 0.93 inches\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eGage Depth\u003c\/strong\u003e: 4.49 inches\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMaximum Extension Rod Length\u003c\/strong\u003e: 6.0 inches\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSetting Ring Diameter\u003c\/strong\u003e: 2.5 inches\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eNumber of Extension Rods Included\u003c\/strong\u003e: 1\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eNumber of Setting Rings Included\u003c\/strong\u003e: 1\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFinish\u003c\/strong\u003e: Chrome\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMeasuring Surfaces\u003c\/strong\u003e: Carbide\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCalibrated\u003c\/strong\u003e: Yes\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eTraceability Certification\u003c\/strong\u003e: NIST\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePackage Dimensions\u003c\/strong\u003e: 10.04 inches L x 6.38 inches W x 5.71 inches H\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eWeight\u003c\/strong\u003e: 8 pounds\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eUNSPSC Code\u003c\/strong\u003e: 41111601\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch4\u003eStandard Information\u003c\/h4\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBrand\u003c\/strong\u003e: SPI\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number\u003c\/strong\u003e: 21-912-1\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"SPIROTHERM","offers":[{"title":"Default Title","offer_id":51691664769330,"sku":"21-912-1","price":832.42,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0270\/4519\/9983\/files\/6a7aaa197f5f3591b87104d57a7b00aa.jpg?v=1788288203","url":"https:\/\/voomisupply.com\/products\/spi-21-912-1-mechanical-hole-micrometer-2-5-3-0-in","provider":"Voomi Supply","version":"1.0","type":"link"}