Soda Water (seltzer) chargers
 

Does anyone use one of these? What is your experience or favorite brand?
I have an isi whipped cream charger and use it all the time and find it is a nice piece of equipment and enjoy the products I can create with it.

I hate tossing a 2/3 full bottle of soda because it goes flat in a matter of hours rather than measured in days or more than a week.