A fixed fastener is suitable for installing roof substructures on roofs covered with trapezoidal sheet metal such as Trimo, Armat and similar. Fastener is appropriate for mounting in the longitudinal and transversal direction. Fastener is screwed onto the trapezoid wave with two screws, whereby the fastener adjusts itself to the shape of the wave. The seal ensures water tightness at the point of fastening. The mounting profile SOL-P03 is fastened onto the fastener with a simple push – without screwing it on! In a set together with fastening screws.