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) 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, 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.