The 0.5  stone is used to force carbonate beverages like beer, champagne or sparking meads with carbon dioxide. The 2.0 stone can be used  to oxygenate wort using an oxygen regulator. The holes in the 0.5 stone are too fine to use it to aerate the wort with an aeration pump. However, compared with the 2.0 micron stone, the 0.5 micron stone will carbonate beer quicker and with a longer lasting head because the bubbles that it creates are smaller. The stones are   1" long and .5" in diameter. 

Force carbonating beverages.
You will need a homebrew kegging outfit with CO2 tank, regulator, lines, and a keg. Simply attach a 24" length of ¼” ID tubing to the gas side dip tube of your keg with a worm clamp. On the other end of the tubing, attach the diffusion stone using another clamp.  There are charts available online and in books for exact levels of temperature and CO2 pressure to achieve desired carbonation levels. Following is an example for average carbonation in beer: Chill the beer to 40 F. Adjust the regulator to 2 PSI and attach the gas disconnect. Every 3 minutes increase the pressure 2 PSI until 12 PSI is reached. At this point the beer will be carbonated, but it won’t hurt to leave it alone in the refrigerator for a few days under pressure. 

If using pure oxygen to oxygenate the wort, Note: High gravity beers may require more time because oxygen does not dissolve as easily in liquids with a high specific gravity. 

Never touch the sintered part of the diffusion stone with your hands. Use sanitized gloves. Oils from your fingers will clog the  holes.

CLEANING: Sanitise stone in boiling water or clean in a non-rinse sanitiser whilst running CO2 or air through the stone.