Applies to screw gauges 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 apply primarily to gauges for screw threads in the regular series such as BS Whitworth, BS Fine, BS Pipe (fastening threads), BA, BSC and BS Conduit. May be applied also to gauges for any screw threads of Whitworth form. Not applicable to gauges for Acme, buttress or round threads. Provision is made for following types of gauges and setting plugs: screw gauges, plain gauges, and setting plugs for adjustable screw ring and thread calliper gauges, GO and NOT GO.