Are existing bottles and cylinders compatible with the SodaStream DUO™ Sparkling Water Maker?
The 1L classic bottle, the 0.7L glass bottle (from the Crystal), the 0.5L bottle and My Only Bottle (0.5L) are not compatible.
With regards to cylinders, you can only use the SodaStream Quick Connect Cylinder with the SodaStream DUO™ Sparkling Water Maker. The screw-system cylinders are not compatible with the SodaStream DUO™.