EK-XTOP Revo Dual D5 Serial EK-XTOP Dual D5 Serial is a fourth generation high-performance aftermarket DUAL pump top (volute) for D5 type water pumps. Using two water pumps in series provides almost twice the head pressure of a single water pump and also guarantees top safety measure - in the case of one pump fails the remaining one will provide sufficient liquid flow to prevent any hardware damage due to overheating. The top is made of quality POM Acetal material, while the tightening nuts are made from CNC machined aluminum. Mounting clamps are made from injection molded ABS. EK-XTOP Revo Dual D5 can be paired with EK-RES X3 150 Lite reservoir. Mounting mechanism with two mounting plates for installing the unit on a 120mm or 140mm fan and easy-to-follow installation guide are enclosed.