To Use: Attach 2 feet of 1/4" tubing from the "gas in" dip tube inside the keg. (Tubing not included). You set your desired pressure on the regulator and gas gets emitted through the .5 micron stainless stone. The bubbles rise through the beer creating so much surface area contact between gas and liquid that the absorption rate is very rapid. This is very similiar to how beer is carbonated in breweries. Stainless 1/2" diameter. Stone is 1" in length. Overall length is 1 7/8"