Tubing Sizes

[BlackEclipse]

The "AN" sizing that you see on tubing is an American standard that was developed many years ago for use on military aircraft. "AN" stands for Army-Navy. The number following the negative represents how many sixteenths of an inch the inside diameter is.

So:

-6 AN = 6/16" = 3/8" inside diameter
-8 AN = 8/16" = 1/2" inside diameter