These fittings fit updated Seastar cylinders and all helm pump to use O-Ring (ORB) type fittings. Before the update all Seastar Solutions helms used NPT fittings. These 316 stainless steel fittings will simplify the installation process and will allow for simple reorientation of fittings after installation. New ORB type helms are clearly marked with “DO NOT USE NPT Fitting”. Cylinder Part Numbers ending in “-3” are the new updated cylinder models that use these ORB fittings.