A mixing segment (12, 12', 12", 12′′′) for a static mixer , the static mixer comprising a plurality of mixing segments (12, 12', 12", 12′′′) for mixing a multi-component material (M, M'), the mixing segment (12, 12', 12", 12′′′) comprising: at least three elongate inlets arranged at least substantially in parallel to one another; and at least three elongate outlets arranged at least substantially in parallel to one another; with a respective elongate inlet being connected to a respective elongate outlet via a respective passage to deflect respective part flows of the multi-component material (M, M') from said elongate inlet to said elongate outlet ; wherein the elongate outlets are arranged such that an elongate extent thereof is rotated by an angle of rotation of at least 45° about a longitudinal axis (A) of the mixing segment (12, 12', 12", 12′′′) with respect to an elongate extent of the elongate inlets , with the longitudinal axis (A) extending from the elongate inlets to the elongate outlets ; wherein a first extent (I) of the respective passage in a direction in parallel to the elongate extent of the elongate inlet gradually reduces in size between the elongate inlet and a constriction of the passage and a second extent (O) of the respective passage in a direction in parallel to the elongate extent of the elongate outlet gradually increases in size between the constriction and the elongate outlet ; and wherein the gradual change in size of one of the first and second extents (I, O) of the respective passage is formed by two walls of the respective passage that are inclined with respect to one another and with respect to the longitudinal axis (A) of the mixing segment (12, 12', 12", 12"'), characterized by at least a part of the walls inclined with respect to the longitudinal axis (A) being formed by a curved part surface (17"). at least three elongate inlets arranged at least substantially in parallel to one another; and at least three elongate outlets arranged at least substantially in parallel to one another; with a respective elongate inlet being connected to a respective elongate outlet via a respective passage to deflect respective part flows of the multi-component material (M, M') from said elongate inlet to said elongate outlet ; wherein the elongate outlets are arranged such that an elongate extent thereof is rotated by an angle of rotation of at least 45° about a longitudinal axis (A) of the mixing segment (12, 12', 12", 12′′′) with respect to an elongate extent of the elongate inlets , with the longitudinal axis (A) extending from the elongate inlets to the elongate outlets ; wherein a first extent (I) of the respective passage in a direction in parallel to the elongate extent of the elongate inlet gradually reduces in size between the elongate inlet and a constriction of the passage and a second extent (O) of the respective passage in a direction in parallel to the elongate extent of the elongate outlet gradually increases in size between the constriction and the elongate outlet ; and wherein the gradual change in size of one of the first and second extents (I, O) of the respective passage is formed by two walls of the respective passage that are inclined with respect to one another and with respect to the longitudinal axis (A) of the mixing segment (12, 12', 12", 12"'), characterized by at least a part of the walls inclined with respect to the longitudinal axis (A) being formed by a curved part surface (17"). <EOS>