This Micro filter is the final almost HEPA type filter. It will filters out 95% of all dust larger than 0.5 micron size. It is large in size and much less expensive than the true HEPA filter which is in most occasions not needed. This Micro filter served our vacuum cleaners and their operators for over 35 years and still going strong. It is vise to change it occasionally because the fresh new Micro filter will improve the vacuum performance. It is not washable, so don’t put it under the tap. You can even filter out dry wall dust. Just make sure to use the paper filter when you pick up dry wall dust (sheet rock dust as it is called south of the border) We used it on the following machines such as the Silento and SL-3 vacuums. To change it, you need to pull it off the motor and push the new Micro filter on to the motor. It is easy and simple.