This Keypak letterbox features an internal draught excluder with integrated brushes to prevent drafts and an internal water seal to stop water leaks. The anti-snap flap opens up to 180 degrees for easy access without the risk of snapping. Its adjustable sleeve design allows it to fit doors between 20mm and 40mm in thickness, 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. The distance between screw holes is 245mm. Installation is easy with adjustable sleeves and provided screws, which should be selected based on door thickness. Please ensure the screw hole spacing matches your existing letterbox.