A fixed fastener is suitable for installing roof substructures on roofs covered with trapezoidal sheet metal roof coverings such as Trimo, Armat and similar. The fastener is appropriate for mild environmental effects. Fastener is screwed onto the trapeze wave with four screws. The seal ensures water tightness at the point of fastening. Mounting profile is fastened to the fastener. In a set together with fastening bolts.