Aluminum AN Fittings

AN (Army/Navy) thread is a particular type of fitting used to connect flexible hoses and rigid metal tubing that usually carries fluid.  AN sizes differ from bolts and other fitting sizes that refers to the diameter of the bolt where the AN fitting refers to the OD of the tube and have different threads. NOTE: AN 37º and SAE 45º are not interchangeable due to the different flaring angles. Mixing them can cause leakage. AN sizes range from -2 (dash two) to -32 in irregular steps, with each step equating to the OD (outside diameter) of the tubing in 1/16" increments.