A compressed air tank, or "carry tank," is a handy workshop or garage tool that allows you to store compressed air in a portable, easy-to-use unit. You fill up the tank with compressed air, using any type of air compressor, then carry the tank to wherever you need it. Compressed air tanks are most commonly used for filling up tires—on cars, bicycles, trailers, ATVs, etc.—but they're also useful for applications using a blow-off tip. The tanks typically are too small for operating air tools for more than a few quick operations.