A straight coupler with 1/8 NPT female threads at both ends. The 1/8 size is the workhorse of instrumentation plumbing, appearing on oil pressure senders, fuel pressure gauges, boost take-offs and water temperature switches. This coupler lets you join two male-threaded items, extend a run, or mount a sender clear of a hot component instead of screwing it directly into the block. As NPT is a tapered thread, it seals on thread engagement, so apply a suitable thread sealant and take care not to overtighten, particularly into aluminium components where the taper can easily split a boss.