This is a true HVLP gun that uses compressed air with a pressure pot. HVLP runs below 40 psi and you can also get a gravity feed cup that attaches to the top of the gun but I do the inside of cabinets and need to get at some weird angles so I use the pot. A three gallon compressor is a little small but the good thing about this type is you don't use air until you pull the trigger so your compressor cycles less. You do need a water separator and no oil in the air so filter it. This setup was around $400.00 but Harbor Freight has some cheapies, that's where I got the pot but threw the gun away. I have a better picture somewhere.