Dasqua 250 X 160 X 50mm Precision Granite Square Grade 00 Dasqua precision granite square squareness is +/-.0.0002mm. Squares are made from a solid block of granite that has been carefully machined to ensure accurate right angles. Granite precision squares come with one large face and two edges that are finished flat and square to each other. It consists of two faces precisely perpendicular to each other, forming a 90-degree angle. A precision granite square is a tool used specifically for checking the squareness (90° angle) between two surfaces or edges. Check the 90 degree squareness of the X and Y axes when used in its horizontal position. Check the perpendicularity of the Z axes when used in its vertical position. Dasqua precision granite squares are commonly used with other measurement tools to verify the squareness of various components and assemblies. They are particularly useful in applications where high accuracy and reliability in squareness measurements are required, such as in precision machining and tooling. This square has a round hole so it weighs less and is easier to handle. An inspection certificate from the manufacturer is provided (not NIST traceable). This square weighs 11 lbs.