Magnetic fastening for simple, quick and easy installation of smoke detectors, for example. Not suitable for detectors with a diameter of less than 7cm or more than 15cm and a weight of more than 250g. Installation without tools, without drilling, without dirt or dust. No risk of damaging lines or cables during installation. Suitable for installation on smooth and horizontal surfaces, not on woodchip or loose plaster. Not suitable for vinyl wallpaper, polystyrene, non-stick, siliconized or Teflon-coated surfaces. The effective contact area must not be less than 25% of the area (approx. 9cm²) of the respective adhesive pad. Two steel plates with 3M adhesive pad. Dimensions: D 70 x 6mm.