Purpose of tiny fuel line fitting?

[wavinwayne]

When I was installing new fuel lines on my old Craftsman chainsaw, as I was dumping the old gas from the tank, the old fuel line, fuel filter, and a little white fitting like the one in the picture fell out of the gas tank. None of the YouTube videos about installing new fuel lines said anything about this little fitting. What is it, and what is its purpose? It's overall length is about the diameter of a nickel.

 

[wavinwayne]

Solved. I found a YouTube video from Fix.com explaining its purpose. It is fitted to the end of the carb return line inside the tank, to keep that line from accidentally pulling out of the hole in the top of the fuel tank. I didn't use it when I ran new fuel lines; I just ran the return line about 1-1/2" into the tank and called it good. Those lines are a tight fit, and there's nothing that should cause that line to pull out of the tank.