Tank Return Hose
But, I can tell you right now that the little grommet/bushing that the aluminum tube part of that slides through to hold it solidly into the overflow tank (like the used one in your pic) is NOT AVAILABLE NEW ANYMORE WHAT SO EVER!!!
Believe me I tried.

My next stop is a boneyard, I guess IF I can find one with 4th gens in it around here (VERY unlikely).





