The specification provides the standard dimensional requirements for obtaining, within practical limits, interchangeability in stopcocks and stoppers for ordinary laboratory and industrial applications. It solely covers ground surfaces dimensional interchangeability, and does not involve design characteristics of the item except where specified. Materials shall be tested and shall conform to the specified values of design, dimension, designation, tolerances, taper, and master gages; as stated in the requirements for Single Straight-Bore Taper-Ground Stopcocks, Single Oblique-Bore Stopcocks, Double Oblique-Bore (Three-Way) Stopcocks, T-Bore and 120-deg Bore Stopcocks, Taper-Ground Flask Stoppers, and Taper-Ground Bottle Stoppers.