Keep your soda machine pumping bubbly goodness, with the Soda Buddy Co2 Refill bottle. This listing is for two (2) of our 4 oz Co2 cylinders. The Soda Buddy Co2 cylinder fits most Sodastream machines of any size. 2 x 4 oz Co2 Bottle. Can fill approx. 32 One liter Soda Bottles, depending on usage and carbonation strength.