AASHTO M 120-08, Standard Specification for Zinc, defines the grades of zinc used in highway construction, principally for hot-dip galvanizing of steel bridges, guardrail, sign structures and drainage items. It addresses chemical composition limits for the recognized grades, the form in which the metal is supplied, sampling and testing, and the marking of lots. Galvanizers, coating inspectors and agency materials engineers refer to it when verifying that the zinc bath and the coating it produces conform to the requirements of the relevant galvanizing specification.