think of air in your marker as a nice cup of tea and now you get that co2 bottle and screw it in this now equates to a homeless fellow whizzing in your tea. you can still drink it but man you will be sorry.
its good to use, just remember to microwave you're ion after every use, 850wt for 3 minutes, then add a table spoon full of water and place back in the microwave for a further 2 minutes.