Our Washers can be used for fixing a wide range of materials on ceiling or wall, including insulation boards, foam panels, sheets, gypsum board and other materials that require load spreading during installation.SpecificationColor: SilverMaterial: IronCenter Inner Diameter: 5.8mm / 0.23"Total Size: 35mmx2mm / 1.4"(1-3/8 Inch)x0.08" (D*H)Packing List: 200 x Washers for Fixing Insulation BoardAdvantageThese flat washers are not just spread the load and prevent damage to wall ceiling insulation board, foam panels, or sheets during installation, but also have a function on fix or fasten the screws through its center hole.Instruction1. Put your insulation board on wall or ceiling.2. Drill a hole on the insulation board and wall.3. Fix the insulation board to the wall by nail(not included).4. Put the washer on the nail to fix and fasten.Note:Please note that this item need to be use with a nail or screw when you using. The washer center hole diameter need to be check before  purchasing.