1. This adapter applies to all soda water machines with TR21-4 interface, used for connecting external carbon dioxide cylinder/tank. 2. New integrated design and improved internal sealing structure avoid the use of any seal glue and are and more . 3. With 8mm male quick disconnect, easy to connect the female , standard size, combined tightly, no air leakage. 4. Made by High-quality materials, oxidation matte treatment makes it lighter, more beautiful, and stronger. Note:Installation guide not included, we strongly recommend you professional installation. Please check as much as possible to make sure the item is what you need. Tips: The product may be updated constantly ,Due To Different Batches, The Actual Product May Have Slight Differences Or Color Differences, Which Does Not Affect Use Colour:Silver Material:Metal Package Contents: 1 x Carbon Dioxide Filling Adapter 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 a little different from the real thing. The measurement allowed error is +/- 1-3cm.