This latest modification of the ACS Flush Fuel Cap (unvented) utilizes a Viton O-Ring as the sealing element between the cap and mounting ring. The Viton O-Ring is compatible with aviation fuels and auto gas. The cap with Viton seal is interchangeable with the old-style cap with rubber gasket. Machined from solid aluminum. Ring may be welded, riveted, bolted or molded to the tank. The bottom of the cap is secured to the bottom of the ring by a safety chain to prevent loss of the cap in flight. Mounting ring flange is 1/8" thick. Ring opening is 2-5/8" dia. Overall dia. 4-3/8".
Made in USA.
I actually use these for my fiberglass motorcycle tanks I design and manufacture. And have for almost 2 decades. The quality has never varied, and there has never been a customer complaint about them.
Per supplier: The filler neck is not included with this fuel cap. There is the cap and a mounting ring only. I think what the customer was referring to is the depth of the mounting flange which is .66".
No, this is the replacement o-ring for the ACS fuel caps P/N#'s 05-01390/05-01391.