Soda CO2 Gas Converter Adapter for Tr21-4 Female to Tr21-3 Male Thread Copper 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 materials, high hardness, wear-resistant, long service life. The thread is tight, precise craftsmanship, stable performance, and installation is simple. If you want to use a sodastream TR21-4 soda bottle instead of a Quooker Cube bottle, this adapter can be used. Threads: Tr21-4 female to Tr21-3 male. Tips: The product may vary slightly between batches; slight differences in color or appearance may occur, which 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.