In short it pumps through a tube with rollers pressing on the outside of the tube. They can be used for situations such as limewater, topoff, or any caustic chemicals that you wouldn't want going through a pump insides. You can set it slow for a dripping or faster. The rpms are 6-600 rpm's. The amount pumped would be dependant on the size tubing that is in it. On a smaller system you would want to set it to a real slow rpm and use a float switch to turn it off because on slow I was putting out about 2 gallons a day running 24/7. It can also turn both directions by a toggle switch so I guess you could use it for water changes etc. It's built very heavy duty and even has round screw access holes where you could even change brushes on the motor. It must weight 20 lbs.