How do I know what size air fitting or hose I need for my tool?

At Bostitch, we usually recommend 3/8" for most applications to guarantee proper air flow to the tools. Lighter airlines can restrict air flow to the tool. Larger tools that are more likely to be used at a higher rate of speed can malfunction because they may be starved for air. Smaller finish tools that are very unlikely to be used at a high rate of speed, will have no problems with the 1/4" light airlines. 1/4" airlines can indeed supply most Bostitch tools at the proper PSI levels, however you will restrict the tools capabilities in high speed applications such as sheathing, decking, and even roofing applications.