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 switch. Made of high-quality materials, high hardness, wear-resistant, long service life. The thread is tight, excellent craftsmanship, stable performance, and installation is simple. Allows use of a sodastream TR21-4 soda bottle in place of a Quooker Cube bottle. Threads: Tr21-4 female to Tr21-3 male. Product may vary slightly due to different batches; slight differences or color variations do not affect functionality. Color: As shown in photo Material: Copper Package Contents: 1 x Soda CO2 Gas Converter 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.