Air brush needles.

[Runway]

At my job I use Micrometers can someone tell me where the best place on the needle to get the Correct size.
I can do the Conversion from MM to inch?

Thank you.

 

[urumomo]

The portion of the needle right at the widest portion of the conical tip .
That fits the spray tip opening exactly --- that's the .3 or .5 mm etc . / whatever the specific tip

You can convert any units you need on the net .
Just type in mm to inch