The Mitutoyo Black Granite Surface Plates are constructed of natural fine-grain granite seasoned for thousands of years, the Mitutoyo Black Granite Surface plates are free from burrs, protrusions, rust, and wringing, making them ideal for precision measurement platforms. The granite plates are twice as hard as cast iron plates and feature superior flatness, non-magnetic properties and longer service life resulting in low maintenance costs and better accuracy. Steel stands and accessories are also available (sold separately).

• AA laboratory grade fine grain, 100lbs. load/sq.ft., no ledge, black granite with accuracies ranging from 50-1000 μin
• A Inspection grade fine grain, 100lbs. load/sq.ft., no ledge, black granite with accuracies ranging from 100-2000 μin
• B Shop grade natural fine grain, 100lbs. load/sq.ft., no ledge, black granite with accuracies ranging from 200-4000 μin

• Natural granite is free from deterioration or dimensional change over time
• Black Granite Plate’s most distinctive feature is its hardness, twice that of cast iron
• Free from wringing effects, so there is no interruption of work
• Since granite is harder, finer grained, and more brittle than cast iron it does not throw up burrs or protrusions if scratched; This ensures a high degree of flatness with no risk of damaging instruments or workpieces
• Use these plates in a stable temperature environment; Since flatness error occurs when there is a temperature difference between the working surface and the underside, avoid working in direct sunlight. Also, do not place a plate in the vicinity of an air conditioner or heater. (Recommended environment: Temperature 20 +/- 1°C, Humidity 58 +/- 2%)