Some regulators have 1/2" Ports on the first-stage for high-flow hoses, but all dive resorts usually carry only the minimum in spare parts, so don't lose out on a vacation dive because you now need to hunt the entire island for the right size hose. This adapter will get you out of trouble in a pinch. Adapter threads into your regulators high-flow port reducing it to a standard 3/8" port in a second. Adapter is made of marine grade chrome plated brass for long life and durability. At times, you can never find the one you need. That is, unless your source is Leisure Pro.