UMA makes a complete line of temperature probes included solid state types. For engine monitoring, we have probes made of brass with thread sized from 1/4-28 to 5/8-18 and various metric sizes, as well as in many different lengths.

Pressure Sensors for Electric Oil, Fuel, Water Gauges. 1/8" npt fitting.

NPT - National Pipe Thread Taper
Note! Pipe thread sizes do not refer to any physical dimensions. The outside diameter of a pipe or fitting must be measured and referenced to a table for size identification.
Note! Inserting a NPT tapered fitting into a port tapped for a straight thread fitting and tightening it can break or severely damage the item the fitting is being installed in.
Pipe Size (inch)	Thread Pitch TPI	Fitting O.D. (inch)	NPT Specifications
1/16"	27	0.313"	Tapered thread 1° 47' Flat truncation of thread roots and crests Thread angle 60° Thread Pitch measured in threads per inch
1/8"	27	0.405"
1/4"	18	0.540"
3/8"	18	0.675"
1/2"	14	0.840"