This is a number 3 thread which has a 3/32" diameter.
This has a tapered needle section and was used with the spray bar that has one hole

There is another Fox needle that looks the same but has a flat on one side rather than a taper.

The needle with a taper fits the spray bar with one hole. The needle with the flat fits a spray bar with 2 holes and will not work with one hole spray bar. We found this tapered needle will work fine with the 2 hole spray bar. You must be sure the holes in the spray bar are horizontal, pointing front and back. and will not work with one hole.