SodaStream CO2 cylinder (TR21-4 (often pin-valve)) vs Tr21: specs compared
Updated 05 September 2026.
4
specs differ
SodaStream CO2 cylinder (TR21-4 (often pin-valve)) and Tr21 differ on 4 specs: designation, size / thread, fitting form, rating / role.
| Spec | SodaStream CO2 cylinder (TR21-4 (often pin-valve)) | Tr21 |
|---|---|---|
| Designation | TR21-4 (often pin-valve) | TR21x4 (soda / SodaStream-style) |
| Size / thread | TR21 x 4 mm trapezoidal, frequently behind a proprietary quick-connect valve | TR21 x 4 mm pitch trapezoidal |
| Fitting form | soda-maker CO2 cylinder | trapezoidal cylinder valve, external |
| Seals on | O-ring on the valve stem | O-ring on the valve stem |
| Rating / role | small refillable soda cylinder brewers repurpose for kegging | small refillable soda-maker CO2 cylinders |
Questions and answers
How do SodaStream CO2 cylinder (TR21-4 (often pin-valve)) and Tr21 compare?
SodaStream CO2 cylinder (TR21-4 (often pin-valve)) and Tr21 differ on 4 specs: designation, size / thread, fitting form, rating / role.