The notation CFM (Cubic Feet per Minute) refers to a volume of air produced by the air compressor at a given pressure or PSI (Pound per Square Inch). The right size air compressor will meet your needs in two essential areas: air flow (CFM) and pressure (PSI). It’s important to get a compressor that meets your needs in both areas – otherwise, you risk damage to both your tools and the compressor itself. Always use CFM and PSI specifications from the nameplate on the product.