Aluminium Letter Box - 305mm WideThe Window Ware Aluminium Letter Box features a fully extruded aluminium frame set, with internal and external sprung flaps. It is 305mm wide and is designed to suit doors between 38mm and 78mm thick. The external flap has been designed to be opened approx. 147, ensuring generous and clear access to the sleeve aperture and it comes complete with an internal nylon brush seal for reduced air filtration. The Alpha Letter Box has a fully extruded