The carbonation cap is highly effective method to add and maintain carbonation in beverages for extended periods of time.The in-built 5/16inch Bart can attach 5/16inch ID tubing and a 0.5 Micrometre carbonation stoneto attach on the end with the portability of being able to move the cap from bottle to beer bottle.Stainless stell make it last forever.Compared with the traditional bottling, kegging, and home seltzer machines,save more time and moneySimple 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.Colour:silverMaterial:Stainless steelPackage Contents:1 x Beer Brewing Carbonation CapOnly the above package content, other products are not included.Note: Light 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.