2-pack Diffusion Aeration Stone 0.5 Micron Homebrew Beer Oxygenation Diffusion Carbonation Stone (best)HIGH QUALITY -- Made of food-grade stainless steel , which made our 0.5 Micrometre aeration stone anti-corrosion and high temture resistant,durable and last a long life POWERFUL FEATURES -- 0.5 Micrometre aeration stone are much more effervescent and frothy than soda guns, get smaller bubbles,evenly diffusion of bubbles, no blockage, strong corrosion resistance,improve the wort fermentation process tremendousl. HOW TO USE -- Must turn on the gas before,and then you can insert oxygen stone into liquid.Attaching the aeration stone barb to a 1/4 inch ID hose, and the other side of the hose can attached to the "in" or "gas side" post or connect it on the CO2 regulator. The beer stone work at lower pressures (about 3-5PSI) IDEAL FOR HOME BREWING -- Compared with 2 Micrometre, 0.5 Micrometre diffusion stone will produce smaller and finer bubbles which can make the O2 or CO2 combine with liquid f. Let your draft beer, soda, coffee and other drinks more delicate, more exquisite and more fresh. USED FOR -- Perfect to force carbonate your kegged beer, or as an aeration stone prior to fermentation, carbonation of Beer or Soda or Juice,works great for Cold Brew Coffee as well.