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Gage Blocks and Standards

Product Features:

    • Precision gage blocks are the primary standards vital to dimensional quality control in the manufacture of parts.
    • Kerley Corporation offers a complete selection of gage blocks available in a choice of rectangular or square, metric or inch and Steel, CRO (chromium carbide) or Ceramic (ceramic) types.
    • Available in Sets or Individaully.

Brown & Sharpe
Fowler (Fred V. Fowler Co.)
SPI (Swiss Precision Instruments)


  • STEEL BLOCKS: are made from high carbon high chrome steel to reduce wear and corrosion.  Precision ground and lapped to provide excellent wringing characteristics.  Thermally stabilized to reduce changes in gage block length over time. Laser-etched with individual serial number for traceability.  A certificate of inspection to ensure each block has been inspected.
  • CERAMIC BLOCKS: Made of Ceramic materials with superior surface quality, that were developed by ultra precision machining techniques solve all problems that the steel gage block had.  Superior hardness, thermal expansion and wear characteristics.
  • CRO (Chromium carbide) BLOCKS: Outwear regular steel and ceramic.  They will not corrode and are very stable and accurate, and have exceptional “wringing” qualities.






  • RECTANGULAR gage blocks are used individually or “wrung” together to achieve desired dimension. Available individually or in sets, Inch or Metric.
  • SQUARE gage blocks have a center hole that can be “wrung” together with a optional tie rod and held together to achieve desired dimension.  Available individually or in set, Inch or Metrics.


GRADE:  The three most common grades of gage blocks used in the machine shops and Labs in the US are:

  • Shop Grade:  B-Grade +/-.00005″ (AS-1, 2)  ( OLD GRADE 3)
  • Inspection Grade: A-1 (0 or AS-1)  ( OLD GRADE 2)
  • Laboratory  Grade: AA (K or 00)  ( OLD GRADE 1)




Rectangular Gage Block Holders with radius jaws and stand available.( shown)
Square block rods,  tie ends and bases available call for details.  818 248-4783. (not shown)




Starrett-True-SquaresTRUE SQUARES (left) used for indexing with ANGLE gage blocks (below).  Angle blocks used to measure any angle.












REFLECTING CUBES: Ideal for 90° indexing or alignment in optical tooling or inspection.





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