303 ss machined to a 63 micro-finish (max.). Commercial Taper Pins have a tolerance of +.0013/-.0007 on the Major Dia. Standard Taper is ¼” per foot or 0.0208” per inch. Standard Steel Taper Pins conform to ANSI/ASME B18.8.2 To find diameter of small end, multiply length by .0208” and subtract result from the large end (Basic) diameter.