The Model 425 also has one-piece encapsulated seat design with an internal filter & PTFE teflon seat.  It features a brass bonnet & body with 2 1/2inch dual scale gauges.  It has a tamper proof, self-reseating internal HP safety valve & conforms to a CGA E-4.  Its' bronze adjusting screw resists corrosion & provides for smooth adjusting.  This is the Model 425 for Oxygen gas with CGA 540 Oxygen tank fitting.