Suitable for several types of hollow walls (e.g. plasterboard, wood, plastic laminate or similar). Preparation of the hole with a hollow cutter with a diameter of 68 mm. Hole centring plate incorporated into the back. Improved retention knockouts, designed for the insertion of pipes with various cross-sections (16, 20 or 25mm) and metal fins for surface mounting the box on walls with a variable thickness of between 1 and 38mm. Fixing lugs for support screws made of metal. Wide range of accessories available: accessories with a template function for tracing the hole, with joining function for mounting in series and installation on the inside of the wall, internal partitions, decorative covers.