Brass Compression Fitting For Plastic, Copper, & Aluminum Tubing, 0.38 Inch Tube OD To 1/4-18 Male NPT, Straight

Copper tubing with a 3/8 inch OD connecting to a 1/4-18 NPT port is exactly what this fitting is sized for. No flaring needed either. Just cut your tubing clean, slide the nut and sleeve on before you insert the tube, push the tube all the way in until it bottoms on the shoulder, then hand tighten the nut and go 2-1/4 turns past that with a wrench. Working pressure runs up to 2000 psi depending on tube size, so it should handle most instrumentation and hydraulic line work without issue.

It is a straight compression male connector that takes 0.375 inch (3/8 inch) tube OD on one end and has 1/4-18 male NPT threads on the other.

This brass fitting is rated for working pressures up to 2000 psi, but that's with a 4:1 safety factor depending on the tube size you're using.

It's rated to handle working pressures up to 2000 psi, which should be suitable for many hydraulic applications. Just make sure your system doesn't exceed that pressure, and you should be good to go.

For metal tubing like copper or aluminum, the working pressure tops out at 2000 psi with a 4:1 safety factor built in. Plastic tubing is a different story. You'll need to cross-check the pressure and temperature limits of your specific plastic tubing against those same thresholds before assuming it'll hold. The fitting itself is rated for that 2000 psi ceiling, but plastic tubing has its own limits that may fall short of that, so the tubing becomes your limiting factor, not the fitting.