The bulkhead fittings have a unique "Recessed Flange" that holds the Santoprene gasket in place, preventing leaks caused by overtightening of the fitting and "squashing out" of the gasket.

The outside threads are also "buttressed" for strength, and left handed to keep the fitting from loosening when turning a fitting into the inside thread. The inside thread goes all the way through to allow fittings, to be installed from the outside or inside.