Made of galvanized iron, the round wall washers are durable, corrosion-resistant and waterproof, which are not easy to rust, deform or break, and can be used for a long time. The foam board gasket is designed with a groove in the middle for fixing screws; and the back is raised, which can be inserted into the backboard surface to fix it in place. A single person can also easily complete the installation. The number of foam board fasteners is sufficient to meet daily replacement and other maintenance needs. The 1-3/8 inch board washers is suitable for fixing and installing backboard, foam boards, interior and exterior walls, ceilings, gypsum boards, composite boards, wall insulation boards, etc., and is widely used in the decoration and assembly of homes, hotels, apartments and other infrastructure. Note: Make sure to install the foam board washers correctly in the required position to provide sufficient support.