This adapter has a female 1/8 NPT thread to accept an aftermarket sending unit. The other side has a male M16x1.5 thread and includes a sealing washer.
We also offer a similar adapter for mechanical temperature gauges. Our 5/8-18 Female to M16x1.5 Male Adapter (Part No. AM2275) has the same male metric thread, but the female thread accepts most American mechanical temperature gauge sensing bulbs.