This microbiological air filter is commonly used as a filter for wort aeration/oxygenation systems but can also fit hand pumps for kegs. Works with either 1/4" I.D or 3/8" I.D tubing and also fits into bung holes. This filter is capable of filtering down to .023 micron at 99.99% efficiency. It is suggested that you replace your air filter when it shows any signs of discoloration. Do not try to clean or run sanitizer through the filter, it will damage the filter.