This 0.5 micron stone is ideal to force carbonate your kegged beer. The barb is 1/4" ID.To Use: Attach 2 feet of 1/4" tubing from the "gas in" dip tube inside the keg and set your desired pressure on the regulator. CO2 pushes through the 0.5 micron pores, enabling the beer to absorb it more readily, leading faster, reliably carbonated beer. Do not touch the stone with your bare hands. The oils in you hands can clog the small pores. To clean and sanitize, boil the stone in water. 316 Stainless1/2" diameter. Stone is 1" in length. Overall length is 1 7/8"