This Standard relates to screw gagues for general and reference use and to setting plugs for screw ring and thread calliper gauges for checking threaded products. The limits and tolerances recommended in This Standard are intended to apply primarily to gauges for screw threads in the regular series such as B.S. Whit; B.S. Fine; B.S. Pipe (parallel threads); UNC; UNF; Metric (S.I); B.A; B.S.C. and B.S. Conduit. They may be applied also to gauges for any screw threads of Whitworth, Unified or Metric (S.I) form. They are not applicable to gauges for Acme, buttress or round threads.