One more piece of important info. Warning: When tightening the hex coupling to "engine fitting" nut, DON'T LET COPPER TUBE SLIP OUT! The ferrule sits between the coupling and engine fitting and is compressed around copper tube when tightening the connection between these two parts. If the copper tube slips out when you are tightening, you'll compress the ferrule making its opening to small to rethread tube through it. To bad, gotta get a new ferrule. Ask me how I know .