Disposable or reusable CO2 cylinder? There are 2 different cylinder types: disposable cylinders that are disposed of and recycled after emptying and reusable cylinders that can be refilled again and again. Many pet shops and gas companies can carry out the refilling. If you live in a region where refilling is a problem, the disposable cylinder can be an alternative. Should the refilling situation improve, you can always convert the disposable pressure reducer into a reusable pressure reducer in 2 minutes by unscrewing the adapter (JBL PROFLORA ADAPT U-M).
JBL refillable CO2 cylinders and many other refillable CO2 cylinders have the following thread connection: W 21.8x1/14
JBL disposable CO2 cylinders and some others (not all!) have the following thread connection: M 10x1
Disposable cartridges are a special case because they have a different thread type: 5/8" UNF. The thread adapter JBL PROFLORA ADAPT U-u201 is intended for pressure reducers like the JBL PROFLORA u201, which are designed to fit these disposable cartridges. This means that instead of the smaller CO2 cartridges with the small pressure reducer, the larger 500 or 1200 g CO2 disposable cylinders can also be used (e.g. JBL PROFLORA CO2 CYLINDER 500 U or 1200 U).
There is another special case for aquarium hobbyists who have Dennerle CO2 pressure reducers for Dennerle CO2 disposable cylinders and can no longer buy the disposable cylinders. JBL has created an adapter so that you can continue to use these pressure reducers, by fitting them on the JBL disposable cylinders which are available almost everywhere.