oil filter can filtrate 99% of 3 micron grain but still have enough flow rate to maintain the low pressure drop.. ZZG series oil filter has a very high capacity of filtration, It can return the cleanness POE oil and mineral oil back to the compressor. The clean oil not only can make sure the oil regulator working properly but also can reduce the abrasion of the compressor. ZZG series oil filter actually can release changing oil for compressor that caused by suspend feculence during the working.