DEMCiflex Computer and Electronic Dust Filters fits over the air intakes of your electronic or computer equipment by way of a built-in magnetic frame. It was designed to fit on the outside of the case and needs no screws, tools or special skills. The design allows everybody to use it no matter what their skill level. No need to open the case or undo anything at all.The intake vents we refer to are the grills or ventilation holes in your computer\'s case where cooling air enters the case. Some of these vents may have fans mounted behind it to direct the airflow in any specific direction and others are unfanned.To determine which vents are intakes we suggest making use of a sheet of paper. With the computer or electronic unit switched on and running, loosely hold a sheet of thin paper in front of every vent opening or grill. If the sheet moves closer to the case and get sucked against it, then you would know that this vent is an intake vent and needs to be filtered. Choose the filter(s) that would best cover that opening.Dust can however enter the case through a myriad of other openings in the case like Optical Drives,USB and other ports that will be very hard to filter. The solution is in setting up your system to be positive pressure and to filter the intakes. In short this means that more air must enter the case where it can be filtered so that the higher pressure inside the case will leak out of every crack and port in the casing so stopping dust from entering there. To read about how to achieve this please see our section on performance/positive pressure.DEMCiflex Computer Air Filters fits by way of a magnetic frame that is part of its structural design. This would adhere directly to the case and in the event that the case is non-ferrous (it has no iron in it\'s composition so that a magnet is not attracted to it) we supply you with a peel and stick magnetic frame that is fitted onto your PC case, around the air intake area. DEMCiflex Dust Filter will attach to this frame, making it easy to remove and clean when necessary. We also offer free Filter Alarm Software that will alert you when the filter needs cleaning.The mesh that acts as filter will separate dust and debris from the cooling air without adversely affecting or restricting the flow.