This Keypak door letterbox is designed for easy installation and effective draught exclusion. It features an internal draught excluder with integrated brushes to prevent drafts and an internal water seal to stop water leaks. The anti-snap flap design allows for 180-degree opening without risk of snapping. Its telescopic sleeve adjusts to fit doors between 40mm and 80mm thick, making it suitable for most uPVC, Composite, and Timber doors with a letterplate slot. The overall dimensions are 270mm x 70mm, with an internal sleeve dimension of 225mm x 37mm. Screw hole centers are 245mm apart. Installation involves cutting the door aperture, separating the halves, placing the exterior gasket, inserting the internal half with brushes, and then the external half with the gasket. Ensure the letterplate covers the aperture and the gasket does not protrude before fixing with the provided short or long bolts. Do not overtighten fixings.