Sr. No Thread Type Size Range Standard1 Metric M 1.0 to M 200 International Organisation for Standardization(ISO)Basic Dimension : ISO:724-1978(E), ISO:9651-1980(E)Gauging Practice : ISO:1502-1978 (E)Indian Standard (IS)Basic Dimension : IS4218 part III- 1976, IS4218 part IV-1976, IS 2334-19752 Unified ( UNC, UNF, UnEF, UNS, UN) No. 1-64 to 4 American StandardBasic Dimension : ANSI ASME B1. 1-1982Gauging Practice : ANSI ASME B2. 1-1982Class of Fit : Plugs : 2B (Medium) Rings : 2A (Medium)British Standard :Basic Dimension : B.S. 1580 1962, Gauging practice : B.S. 919 Part I19603 Whit worth (BSW, BSF) 18 to 4 Basic Dimension : B.S. 84-1956