A 1/8 inch NPT male to male adapter, threaded on both ends to join two female NPT ports or to convert a female port into a male one. It is one of those parts you do not plan for but frequently need: a sender that presents a female port where the block presents another female port, a gauge assembly that will not thread together, or an adapter stack that needs one more link. At 1/8 NPT it covers the small threads used for pressure senders, temperature switches, gauge feeds and vacuum ports across a huge range of engines. Being a tapered thread, use a suitable liquid sealant or PTFE tape and tighten to seal without overstressing the female port.