This is the Zeagle Tank Fill Adaptor 330-FA10-AA Connection for Standard Scuba Valve Filling Whip Features: Converts Zeagle RaZor fill plug for use with yoke style fill station Brass construction Not for in-water use Part #: 330-FA10-AA Since the Zeagle RaZor is both a Regulator and a Valve, a means has to be provided to fill the cylinder that the RaZor is screwed into. Each RaZor comes with a filling adapter that provides either a connection point for a standard Scuba Valve Filling Whip (330-FA10-AA, shown above) or a connection to a standard tank valve (330-6050). A cap is unscrewed from the Filling Probe on the RaZor and the filling adapter is connected in its place.