With ProConnect technology in the Fusion PC gun, the entire fluid section including the side seals and all associated o-rings are replaced in a single cartridge compared to individual parts like the Fusion AP. This allows you to rebuild you gun like a pro and finish your job every time. The Graco Fusion PC has all the benefits of the Fusion AP, but with 13 simple parts that combine into one disposable ProConnect cartridge. The mixing chamber is easily accessible and you don't need to remove the fluid housing in order to access it! Spend less time rebuilding and easily change out your cartridge to keep spraying.