Our .5 micron stone is ideal to force carbonate your kegged beer, or as an aeration stone prior to fermentation. The barb is 1/4" ID. 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. 316 Stainless 1/2" diameter. Stone is 1" in length. Overall length is 1 7/8" Sanitizing your Diffusion Stone: To properly sanitize your stones, we recommend you run it in a sanitized solution for 5 minutes. If the stone becomes clogged we recommend boiling the stone for 1-3 minutes to help break down anything within it. If boiling is not an option, we recommend soaking in Star San. Star San will remove a majority of surface contamination/bacteria, but will not sanitize the interior of the stone which may or may not be contaminated. Please note that you do not want to touch the stainless stone portion with your hands. The oils on your fingers can actually clog the small pores in the stone.