This extender nut has male 5/18-18 threads that fit the gauge port on oil filter heads and temperature adapters such as our
Remote Filter Head With 5/8-18 Gauge Port (Part Nos. 1220 and 1221) and our Inline Temperature Gauge Adapters (Part No. 1227). The female 5/18-18 port has the proper seat for Stewart-Warner and Auto Meter mechanical temperature gauges.