The DEMCiflex Fractal Design R5 magnetic dust filter 6 piece set is custom made for a perfect fit. Filters are included for the double front, 3 vent top, rears large and small, optical ports front as well as the bottom. They can be fitted to the inside or outside of the mounting, depending on your preference, and are ideal if the area on the case where the it needs to fit is made of a non-ferrous material, such as aluminium or acrylic.It allows for simple one-piece construction with magnetic adhesion, is reusable and easily removed for cleaning.