$iG$io and $7Inot go$7R screw plugs, rings, and calipers; adjustable type setting plugs for screw rings and calipers; check plugs for solid screw rings; $ig$io and $7Inot go$7R plain plugs and calipers. Inspection of product threads, use of various gauges, inspection of product threads by direct measurement, gauge tolerance tables. Appendices: illustration of tolerance zones, effective diameter equivalent of pitch and angle error, gauges for plated screw threads, setting to the size adjustable screw ring gauges, determining limiting sizes of gauges and setting plugs, comparison between British and American gauges.