For sale is a lot of TWO surplus Universal Valve Co. Type 521DP / 522DP Double Poppet Safety Valve. (1) 1-3/4" NPT Diameter external threaded end and (1) 1-3/4" NPT diameter internal threaded end. Zinc plated, cast iron body and top. Buna-N seal. NOTE: These valves are believed to be unused / never installed. What you see in the photographs is what you will receive. Feel free to ask any relevant questions. NOTE: We have several identical and similar items available: please check our other listings.