¼” NPT Female to 3/8 O-Ring Please Note: This version is a little lighter duty than the other one listed. It is still good quality. This adapter has ¼” npt Female on the one side and 3/8” o-ring on the other. This 3/8” o-ring on this one is the same as your scuba regulator. This allows you to screw this into your scuba regulator and take full advantage of any ¼” npt accessory. This adapter will allow you to make a long hose for hookah; a cleanout for your sprinklers; you name it. Better yet, as I said earlier, convert it to quick connect and make a million different adapters.