Your instruction manuals refer to PSI and CFM. What's the difference? Support October 03, 2020 18:20 PSI = Pounds Per Square Inch and is a measurement of pressure. CFM = Cubic Feet per Minute and is a measurement of volume. Related articles My pneumatic nailer / stapler will no longer drive the fastener completely; it seems to be losing power. Can this be repaired? How do I know what size air fitting or hose I need for my tool? BTE550 instructions What does the term "Low Fastener Lockout" mean? How can I tell when my Bostitch tool was manufactured? Comments 0 comments Please sign in to leave a comment.