1/2" male thread x 1/2" Barbed slip on fitting is used with many residential Fleck Valves.
A flexible drain line tubing ( 1/2" I.D. x 5/8" O.D. ) is used with this fitting.
This is the type of fitting normally included with your Fleck 5600 Valve Purchase.
Note: Teflon Tape is the recommended thread sealant to use on this connection.