Abstract: The triangular warning sign is a tripod forming a pyramid with ribs connected to each other by upper ends and framed by a flexible sheath with light-reflecting flexible strips. The ribs form telescopic legs with a hinged connection to each other. For a fixation of the completely unfolded legs it is provided with a fixing strut. The light-reflecting flexible strips are attached to the legs on two lateral sides and form a red polymer cloth frame. On the front side, rails are attached to the legs by lower portions and connected to each other by their upper ends, at their upper portion the rails are connected to the legs. A flexible polymer cloth strip is attached to the rails, formed as a red frame consisting of an outer light-reflecting band and an inner fluorescent band, surrounding the hollow centre on three sides and having the shape of concentric equilateral triangles.