Soda CO2 Gas Converter Adapter for TR21-4 Female to TR21-3 Male Thread Copper Tank Output Good sealing performance, no air leakage when connected with the cylinder, more convenient to use. Mainly used for the thread adapter of the soda machine cylinder, and can also be used as an air source connector. Made of high-quality copper materials, high hardness, wear-resistant, long service life. The thread is tight, precision crafted, stable performance, and simple to install and use. Allows use of a sodastream TR21-4 soda bottle in place of a Quooker Cube bottle. Threads: TR21-4 female to TR21-3 male. Note: Product may vary slightly between batches; minor differences in appearance or color may occur but do not affect functionality. Color: As shown in photo Material: Copper Package Contents: 1 x Soda CO2 Gas Converter Adapter Note: Light reflection and different displays may cause the color of the item in the picture to appear slightly different from the actual item. Measurement error allowed is +/- 1-3 cm.