Jacob Edson invented the diaphragm pump back in 1859 and we still make pumps that use the same concept today. Edson's manual pumps have the highest capacity discharge per stroke on the market. Built tough for years of service and are designed for simple on-board maintenance. These pumps are self priming and have a large flow-through inlet and discharge passages for virtual clog-proof operation. With the reinforced diaphragms and valves have a long life of over 3,000,000 cycles and come in 1-1/2" or 2" NPT ports. Made from marine-grade bronze or anodized aluminum Edson's pumps are made to last.