Two cylinder cast iron two stage air compressor pump.
This is a 5 horsepower pump that will deliver up to 18.71 CFM
This pump is most commonly used on compressor tanks of 80 gallons or larger in size unless being used with a gas engine, where in most cases, the tank will be much smaller
It can be used with a 12 HP or larger gas engine or a 220-volt 5 horsepower electric motor or larger