Abstract: Profile connecting systems having profile bars and connecting elements and assembly thereof. The profile bars may have at least one axial elongated hole and on the profile outer sides slots for nut block connections. Profile connections may be assembled by inserting and fixing an abutment, for example, a self-cutting threaded insert, into the bore of an axial elongated hole in a first profile bar. Adjacent to the installation length of the threaded insert and of the head of a screw, an axially running wrench opening may be provided in the tubular body of the axial elongated hole. The length and width of the wrench opening may permit guidance therethrough of a assembly tool, for example, socket wrench with joints or with a substantially spherical socket wrench head with flats, at an insertion angle to the longitudinal axis of the profile bar and the coupling of the socket wrench to the head of the screw.