AFL Series is an FNPT by a triple barb elbow, and is molded of NSF-listed Natural Nylon or FDA listed Black Polypropylene. FNPT sizes are 1/8 inch, 1/4 inch, 3/8 inch, 1/2 inch, and 3/4 inch. Barb sizes are 1/4 inch, 3/8 inch, 1/2 inch, 5/8 inch, and 3/4 inch. The working pressure for both materials is 150 psi. These adapters should not be used for compressed gasses.