The 13.5 cm long cable carrier marks the box to be installed on the second drywall. The cable carrier is glued to the first plasterboard wall. The beveled mandrel pierces the insulation and the second drywall so that the placement of the first box is clearly visible, eliminating the need for a second measurement on the finished wall. The mandrel also serves as a centering hole for drilling out the box - without any pilot drilling. For multiple drillings, we recommend using a drilling template to save even more time.