http://tinyurl.com/mpwonx8
Earl's 581806 Blue Anodized Aluminum -6AN Tube Nut - Set of 2
Designed for a -6AN tube and has a fitting size of -6AN
Manufactured from aircraft quality aluminum that is lightweight, but durable
AN tube nut seals on the flare (cone), not the threads
Should not be overtorqued to prevent damage to part
Made in the USA