The filter on the System One milking machine filters air coming from the tank into the pump. As a normal part of the milking process, tiny bits of dirt, dust, even metal shavings can circulate through the system, and the filter traps these. Our filter consists of a small mesh screen and a piece of folded cheese-cloth. As part of your routine maintenance, open your filter and check the cleanliness of the cloth once a month. Replace the cheese-cloth as needed, and be sure to put the screen and cheesecloth back in the filter exactly as you found it.