Aquastream Compatible Zip 91295 Sparkling CO2 Replacement Cartridges for Zip Hydrotap and ChillTap residential and commercial Zip water systems. However, as these cylinders are classed as dangerous goods, sometimes they do take a couple of days longer. Each kit contains two Sparkling Replacement Canisters containing 2.2L each. The CO2 Carbon Dioxide Sparkling cartridges can be replaced easily by the owner following the DIY instructions provided in the kit. Compatible with and identical to the Zip CO2 Model 91295 (GTCD22Z). Also identical to the Billi 996912 and Billi 996911 cylinders and can be used in your Billi system. Leaking CO2 Cylinder? If CO2 is leaking out of a newly installed cylinder, this likely means that regulator seal requires replacing. This is a common issue and most of the time, simply replacing the seal will fix the leak. Consider purchasing a spare here.