The new PS20 102-mm (4-in.) Original Metal AODD Pump equipped with the energy-efficient Pro-Flo SHIFT Air Distribution System has a clamped configuration for ease of maintenance, diaphragm replacement and cleaning. The Pro-Flo SHIFT’s air control spool automatically restricts the amount of air going into the pump during the latter part of each stroke, which eliminates chamber over-filling and lowers power consumption.