u/Important_Anybody224

I'm replacing a hot water tank for a dispenser and the old unit has this metal piece (circled in pic) that prevents the nut from coming off the inlet. What is this part called and is there an alternative solution? It came with a quick connect fitting but that doesn't work with the braided line that I have coming from the faucet.

Yes, I mangled the copper line on the old unit after trying to remove that piece.