SodaStream CO2 cylinder (TR21-4 (often pin-valve)) vs Restrictor Plate: specs compared
Updated 05 September 2026.
5
specs differ
SodaStream CO2 cylinder (TR21-4 (often pin-valve)) and Restrictor Plate differ on 5 specs: designation, size / thread, fitting form, seals on, rating / role.
| Spec | SodaStream CO2 cylinder (TR21-4 (often pin-valve)) | Restrictor Plate |
|---|---|---|
| Designation | TR21-4 (often pin-valve) | 5-hole restrictor plate |
| Size / thread | TR21 x 4 mm trapezoidal, frequently behind a proprietary quick-connect valve | internal disc, typically with five small holes, sized to the stout faucet body |
| Fitting form | soda-maker CO2 cylinder | internal flow-restricting disc |
| Seals on | O-ring on the valve stem | sits captive inside the stout faucet, not a threaded joint |
| Rating / role | small refillable soda cylinder brewers repurpose for kegging | the part that de-gasses nitro beer as it is forced through its small holes |
Questions and answers
How do SodaStream CO2 cylinder (TR21-4 (often pin-valve)) and Restrictor Plate compare?
SodaStream CO2 cylinder (TR21-4 (often pin-valve)) and Restrictor Plate differ on 5 specs: designation, size / thread, fitting form, seals on, rating / role.