These cylinders follow the current market standard size and will fit most sparkling water and soda water machines on the market including the Aarke Carbonator itself and SodaStream, Levivo, Drinkmate, Phillips and all other Home Use Carbonators. You will receive 4 gas cylinders which should last approx 240 litres depending on how much carbonation you enjoy. Returning your empty cylinder You can now drop off your empties for FREE to your local participating convenience store in Ireland. No need to print anything, it couldn't be easier. Please note we require 4 canisters returned per package. Simply go https://coll8.drop2shop.ie/ Select The Kind as the retailer Find your handiest convenience store Fill out the online form and that's it Specifications Store your Aarke bottles in the refrigerator to chill before carbonating--cold water holds more CO2. Store your CO2 cylinders in a cool, dry environment. Avoid storing in direct sunlight or close to other heat sources.