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 the air source switch. Made of high-quality materials, high hardness, wear-resistant, long service life. The thread is tight, advanced technology, stable performance, and the installation and use is simple. Compatible with Sodastream TR21-4 soda bottle for use instead of Quooker Cube bottle. Threads: Tr21-4 female to Tr12-3 male. Product may vary slightly due to batch updates; differences in appearance or color do not affect functionality. Color: as shown in photo. Material: copper. Package includes: 1 x Soda CO2 Gas Converter. Content limited to what is listed; other items not included. Actual item color may vary slightly due to lighting and display differences. Measurement error allowed within +/- 1-3cm.