Both the tube nut (AF818 series) and tube sleeve (AF819 series) must be used in conjunction with each other in order for them to work. Slip the Tube Nut onto the hard line first, followed by the Tube Sleeve. Then use a 37���� flaring tool to flare the end of the tubing. When you screw the Tube Nut onto a male AN fitting, the Tube Sleeve will protect the end of your hard line.
