The Engine-Air Pump allows engine compression to work in place of disposable CO2 cartridges. A collection of adaptors is provided; one will fit into an open spark-plug hole. Then you connect the adaptor hose, crank up the engine and let the compression stroke do all the work. Obviously, this kit is best suited to bikes whose spark plugs are easily accessible and won't, naturally, work on a single-cylinder engine. The kit also contains rope-type plugs, tube patches, glue and tools.