The material used is a solid metal box made of painted sheet steel 0.5 mm thick, which protects all types of cables from external mechanical damage. The box is fixed by means of dowel nails or an installation gun. The tight fixing eliminates the need for additional fasteners and provides reliable protection against vandalism and breakage. The semi-circular shape is less injurious, more robust than other shapes and makes better use of the space within the cable routing system. This reduces the amount of protrusion from the wall. We have selected two sizes to fit 16 and 22 drills so that the radius of the cable duct matches the floor opening and covers the lines tightly.