Abstract: A mixing segment for a static mixer includes inlets and outlets connected by a passage to deflect respective part flows of a material from the inlet to the outlet. Each of the outlets arranged such that an extent thereof is rotated by an angle of rotation of at least 45°. A first extent of the passages gradually reduces between an inlet and a constriction of the passage, and a second extent of the passage gradually increases between the constriction and the outlet. The reduction in size of the first extent or the increase in size of the second extent is formed by two walls of the passage that are inclined with respect to one another and with respect to the longitudinal axis of the mixing segment, with at least a part of the walls inclined with respect to the longitudinal axis formed by a curved part surface.