Soda CO2 Gas Converter Adapter for TR21-4 female to TR21-3 male thread. Copper construction with good sealing performance, ensuring no air leakage when connected to the cylinder for convenient use. Designed primarily as a thread adapter for soda machine cylinders and can also function as an air source switch. Made from high-quality materials with high hardness and wear resistance for long service life. Features tight threading, excellent craftsmanship, stable performance, and easy installation. Enables the use of a Sodastream TR21-4 soda bottle in place of a Quooker Cube bottle. Thread specification: TR21-4 female to TR21-3 male. Material: Copper Color: As shown in photo Package includes: 1 x Soda CO2 Gas Converter (other items not included) Note: Product may vary slightly between batches in color or appearance due to updates; this does not affect functionality. Lighting and display differences may cause slight color variations. Measurement tolerance: ±1–3 cm.