NPT (National Pipe Thread) fittings seal by the intentional interference created by the tapered threads meshing together. 

NOTES:
1. The 14-0359 is commonly used with the popular Bosch PST-F1 absolute fluid pressure/temperature sensor. It is also compatible with the 2018+ Mustang GT fuel rail sensor.
2. Information regarding a 3/8" NPT fuel pulse damper (P/N: 14-0128) can be found HERE.
3. Always use a small amount of PTFE paste or tape on NPT threads and tighten to finger tight, then add another 1.5 to 3 turns until tight.

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