The ROwasher Microbial Filter Mat is the key component of the ROwasher parts cleaning system. It is designed to deliver our microbes into the ROwasher system where they break down or eat oil and grease washed off dirty parts. The top white Filter Mat layer is designed to trap large particles up to 50 microns whilst the blue layer provides support for the microbes to breed and grow a microbial reservoir to be released into the ROwasher. There are different types of microbes in our Filter Mat designed to degrade different types of oil and grease. All are Bio-Safety Level 1 Microbes which are non-pathogenic or no risk to humans or animals. The ROWASHER MICROBIAL FILTER MAT must be changed every month to keep the microbe colony healthy and maintain the cleaning performance of ROwasher.