2 Micron Diffusion Stone. Works with both aeration pumps and Compressed Oxygen Cylinders. Diffusion stones work great for oxygenating and also for carbonating your beer. In order to carbonate in your Cornelius keg, simply connect 2 foot of gas line into the gas in dip tube and attach the stone to the other end. Crank the Co2 very slowly (about .5 a psi at a time). For Oxygenating, either attach the stone to an air pump or to an oxygen tank. The diffusion stone can then be easily removed from the line and boiled, ensuring a bacteria free environment for your homebrew.