You may also like. 5.5HP Twin Cylinder Air Compressor Pump Head 21CFM Single Stage Hotsale blue. US 5.5HP 21cfm 115PSI V Type Twin Cylinder Air Compressor Pump Head Single Stage. 5.5HP 21cfm 115PSI V Type Twin Cylinder Air Compressor Pump Head. Power: 4000W, 5.5HP. Exhaust volume: 600L / min (21.1cfm)….