600GS-16 (Globe) and 600AS-16 (Angle) Series are Stainless Steel, reduced port, dual chamber basic valves that incorporate a two-piece telescoping disc and diaphragm assembly. When pressure is applied to the upper diaphragm chamber and released from the lower diaphragm chamber, the valve travels to a closed position. When pressure is applied to the lower diaphragm chamber and released from the upper diaphragm chamber the valve travels to a full open position. The lower portion of this two-piece assembly is a mechanical check feature, which acts independent of diaphragm position or pilot control system, and provides immediate check action when flow ceases. The reduced port design offers improved low-flow performance and cavitation resistance. Stainless Steel construction provides superior corrosion resistance, a lightweight alternative to conventional heavy iron valves, extended diaphragm life, and reduced frequency and labor costs associated with traditional maintenance repairs.