$7IGo$7R and $7Inot go$7R screw plugs, ring and caliper; check plugs for adjustable screw rings and calipers; check plugs and wear check plugs for solid screw ring gauges; $7Igo$7R and $7Inot go$7R plain plug, caliper and ring gauges. Uses of various types of gauges , tolerances, general design features. Inspection procedures and settlement of disputes.