A basic system consists of some insect mesh a frame with a channel, a ‘spline’ or ‘cord’ to hold the mesh in place and a method of fixing the screen in place. The fly screen is fitted over a door or window to prevent insects from entering.
The clever thing about screen systems is that by putting a specific type of mesh into a screen frame, we can create a screen to deal with a specific problem. For example, a standard insect mesh (16 x 18) will prevent flies, wasps, bees and mosquitoes from passing through, however to prevent midges passing through a finer 20 x 30 mesh is required. So the screen frame stays the same but the mesh changes.