With flatness tolerances thinner than a strand of hair, these plates give you the flattest possible surface for accurate measurements. They’re typically used as a reference plane to inspect finished products and calibrate precision measuring tools, such as height gauges and dial indicators. Unlike metal plates, these granite plates won’t rust or interfere with nearby electronics. They also won’t warp when temperatures fluctuate. To maintain their flatness and finish, rotate plates regularly and apply granite cleaner (not included) to remove particles without leaving a residue.

Also Available: Other plate sizes. Please order 2245A999 and specify grade, length, width, thickness, and with or without ledges.

Laboratory-Grade AA Plate—Best for precision inspections and quality-control work in calibration labs. These plates have the tightest flatness tolerance for the highest level of accuracy.

Inspection-Grade A Plate—Your go-to for general inspections and quality-control work. These plates are slightly less precise than grade AA plates with double the flatness tolerance.

Toolroom-Grade B Plate—Suitable for checking routine measurements throughout a shop. These plates are the least precise with four times the flatness tolerance of grade AA plates.

Black—Harder and denser than red plates to handle heavier loads, such as large bearings and other machined parts.

Rectangular Plate with Two Ledges—Choose these plates if you need to mount fixtures and instruments with a clamp.

Surface Plate Covers—Prevent dust and debris from accumulating on plates when you’re not using them.

Surface Plate Stands—Attach to plates at three support points to keep them from sagging and warping, as specified in Fed. Spec. GGG-P-463-c. The welded steel construction offers greater strength, durability, and stability than economical alternatives such as block and wedge systems.