Are C02 pumps a single use product? i.e. does the cartridge need to be replaced after every use?
Innovations Ultraflate Plus Pump
In theory, you could part use a cartridge and leave it in the inflator for next time. However, in practice, a cartridge only just fills a 23c tyre, and in any case, would you really want a pierced high pressure cartridge kicking about under your saddle, relying on the valve in the device?