fuel line reducer

I do not want to force anything on this line. So I'll post.

My assumption was that I can/could replace this fuel line reducer by removing the 'setscrew'... but now I'm not 100% sure that is it's purpose and figured I had better just ask.

Do I need to take this complete line out or will this turn off?

Also removing that screw there was teflon-like tape used. There must be something better than tape on a fuel line isn't there?

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