Measuring tool or component such as a base or head attachment are often made from a cast metal such as alumimum, zinc or cast iron. The term "cast iron" refers not to a single material, but to a family of materials whose major constituent is iron, with important trace amounts of carbon and silicon. Cast irons are natural composite materials whose properties are determined by their microstructures - the stable and metastable phases formed during solidification or subsequent heat treatment. The major microstructural constituents of cast irons are: the chemical and morphological forms taken by carbon, and the continuous metal matrix in which the carbon and/or carbide are dispersed.