Magnum™ flyscreens are covered here by one part in two pack sizes: a black flyscreen retaining spring clip, sold singly and in a 10 pack. A one-part range says something specific, which is that the clip is the thing that fails. These small sprung clips hold the insect mesh frame into the window opening, and they lose tension, go brittle or snap, which is why a screen starts rattling or drops out of the reveal while the frame and the mesh are still perfectly sound. Before ordering, pull one of the old clips out and check its width and the shape of the spring leg against the product images, then count how many the screen uses. Most openings take several per side, so the 10 pack is usually the sensible quantity.