Use this 2 micron oxygen stone with an oxygen source or aeration pump to provide your yeast with oxygen pre-fermentation. The barb is 1/4" OD. (Note: if you are using an aeration pump, we recommend a "deep water" type for aquariums, as these will have the necessary PSI to force the air through the stone and into the wort) Sanitizing your Diffusion Stone: To properly prepare your stone for use, we recommend you boil in water for 1-3 minutes. By heating the stone to boiling temperatures you kill all possible contaminants that may be hidden within the stones micro pores. Using a surface sanitizer is not a guarantee from contamination. Boiling also greatly reduces clogging issues by helping to remove sugar residue. If boiling is not an option, we recommend soaking in Star San, which 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.