Four classes of pins are specified and requirements for the chemical composition and physical properties of the material are given for sizes from 1/16 in. x 3/8 in. to 7/8 in. x 8 in. Reference is by the fractional size of the diameter of the larger end and, for convenience, a comparison of this standard method with the non-preferred method of reference by numbers is given in an appendix. The selection of suitable drill sizes is covered in a further appendix.