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 the air source switch. Made of high-quality materials, high hardness, wear-resistant, long service life. The thread is tight, with superb craftsmanship and stable performance; installation and use are simple. If you want to use a sodastream TR21-4 soda bottle instead of a Quooker Cube bottle, you can use this adapter. Threads: Tr21-4 female to Tr21-3 male. Tips: The product may be updated due to different batches. The actual product may have slight differences or color variations, which do not affect use. 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 allowed error is +/- 1-3 cm.