Product Description: The carbonation cap is highly effective method to add and maintain carbonation in beverages for extended periods of for time. The in-built 5/16" Bart can attach 5/16" ID tubing and a 0.5 micron carbonation stoneto attach on the end with the portability of being able to move the cap from bottle to beer bottle. Product Advantages : Stainless stell make it last forever. Compared with the traditional bottling, kegging, and home seltzer machines,save more for time and money Simple to use,fill a standard 2L bottle with homebrew (or liquid), attach the cap and CO2 system, and shake. Carbonating home brew has never been easier Use a standard plastic bottle and this carbonation cap for an easy and effective carbonation process. Specification: Color: Silver Material: Stainless Steel Size: As the picture Quantity: 1Pc Note: Size for manual measurement, there may be a 0 to 2 for cm error, belongs to the normal phenomenon. And due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you Package includes: (Without retail package) 1 x carbonation