Assembling the smoke alarm without drilling, screwing or noise._x000D_No damage to the roof or cables / ducts._x000D_Very easy and fast assembly with two self-adhesive magnetic plates._x000D_Easy smoke alarm removal (for tests, battery replacement, etc.)._x000D_Not suitable for vinyl, styrofoam, non-stick coating, silicone or Teflon coated wallpapers. Suitable only for smoke alarms with a diameter of less than 8 cm.