Abstract: The present invention refers to a lens for a signal light, which lens is configured to convert a first distribution of light rays emitted from a light source (23) into a second distribution of light rays. The lens comprises at least three sectors and each lens sector has at least one internal surface (42i-44i) and at least one corresponding external surface (42e-44e) arranged to convert the first distribution into the second distribution. The internal (42i-44i) and external (42e-44e) surfaces form an overall internal surface (40i. 140i) and a corresponding external surface (40e, 140e) free from undercuts.