Wilden, part of PSG, a Dover company, releases the PS20 102 mm (4-inch) Original Metal AODD Pump equipped with the energy-efficient Pro-Flo SHIFT Air Distribution System (ADS). Wilden, part of PSG, a Dover company, releases the PS20 102 mm (4-inch) Original Metal AODD Pump equipped with the energy-efficient Pro-Flo SHIFT Air Distribution System (ADS). The Pro-Flo SHIFT is designed to optimize air configuration to lower energy and operating costs and achieve up to 60 percent savings.