Excellent sealing performance; no air leakage when connected to the cylinder, making it more convenient to use. Primarily used for the soda machine cylinder's threaded adapter, it can also serve as an on/off switch for the air source. Made of high-quality materials, boasting high hardness and durability for a long lifespan. The thread is tight, featuring superb engineering, stable performance, and easy installation and use. Use this adapter if you want to use a Sodasteam TR21-4 soda water bottle instead of a Quooker Cube bottle. Threads: TR21-4 female to TR12-3 male. Note: The product may be continuously updated. Due to different batches, the actual product may have minor differences or color variations, which do not affect its use. Color: As shown in the picture Material: Copper Package Contents: 1 x Soda CO2 Gas Converter Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture to be slightly different from the real thing. The allowable measurement error is +/- 1-3 cm.