Because of the inner foam core of Wedi panels, washers MUST be used when screwing or nailing into or through the panel.The Wedi Wall Installation Kit includes the necessary hardware to install your Wedi directly to another substrate such as a wall or backsplash. The kit include 4 Wedi Washers and a variety of screws and wall anchors for direct installation of Wedi- up to 24" x 24"- to a wall or other permanent substrate. Detailed instructions included. SHIPPING COSTS INCLUDED! However all International requests for this product will be charged for the shipping out of the country.