Covers the Normal series of Unified precision hexagon bolts, screws and nuts having Unified screw threads in a range of nominal sizes from 1/4 inch to 2 inch inclusive. The dimensional requirements of this Standard apply both to ferrous and non-ferrous bolts, screws and nuts. Mechanical properties are given only in respect of steel bolts, screws and nuts, and the finishes in which they are normally supplies are described in Clause 3.