SS-600-1-4, 6-4 FBZ-SS, 6MSC4N-316, DCT-6-4-SS. I bet you recognize at least one of these numbers. These are competitive item numbers from some of the big vendors who make tube fittings. And from years of experience you might recognize what specific fitting this is: 3/8” tube connection by ¼” male NPT, straight fitting.
“Hey, hand me a big wrench.”
“It doesn’t matter, just hand me a big wrench.”
“What do you mean it does not matter?”
“I am going to use it as a hammer anyway!”
This has always been a funny joke, but it illustrates a point.