- Surface Plates & Granite Shapes
- Reference Masters
- Height Masters
- Bench Centers
Surface Plates
Surface plates are a fundamental measuring tool. They provide a nearly perfect plane on which other measurements can be made. Surface plates are available in a variety of tolerance classes:
- Grade AA is the most precise, used in laboratories
- Grade A is for general inspection work
- Grade B is for shop floor work
See: ASME B89.3.7-2013 (the older standard was Federal Specification GGG-P-463c)

Granite Master Squares
Used for checking squareness of machine tools.

Granite Parallels
Useful for creating inspection datums. Often used when a part has protrusions on an otherwise flat surface.

Granite Straight Edges
Used to compare flatness and straightness of long parts such as machine bedways.

Granite V-Blocks

Granite Six-Face Cubes

Granite Angle Plates
Granite angle plates can provide a perpendicular surface to the plane of a surface plate.

Gage Blocks
Gage blocks are made with extraordinary precision to very tight tolerances. They can be combined to produce a wide range of sizes.
Gage blocks are made to standard grades:
- 00 – Most exact tolerance
- 0 – Suitable for inspection
- AS -1 – Between shop floor use and inspection
- AS-2 – General shop use
See ANSI/ASME B89.1.9M (and the older U.S. Federal Specification GGG-G-15C). Former grades were AAA, AA, A, and B and .5, 1, 2, 3.

Gage blocks must be wrung together to produce accurate results.

Plug & Pin Gages

Gage Balls

Ring Gages
Height Masters
Height masters are used to calibrate height gages.
Bench Center

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