This adaptor allwos to use an accessory threaded in 9/16"-18 male to 3/8"-24 male.
Threaded adaptor 3/8"-24 male to 9/16"-18 female
Allows the usage of a 9/16" male accessory to 3/8" male such as :
- a T adaptor - a Flow Stop - a 9/16" hose mâle as regulator type - etc...