An anti-Met antibody fragment comprising a single antigen binding arm and an Fc region wherein the Fc region comprises a complex of a first and a second Fc polypeptide, wherein the antibody fragment comprises: (i) a first polypeptide comprising one humanized light chain variable domain, and one human light chain constant domain, wherein the humanized VL domain is fused to the human CL domain in the N- to C-term direction, and wherein the humanized VL domain contains three complementary determining regions (CDRs) having amino acid sequences as set forth in SEQ ID No.: 1, 2 and 3, and wherein the humanized VL domain has an amino acid sequence as set forth in SEQ ID No.: 7; (ii) a second polypeptide comprising one humanized heavy chain variable domain, one human heavy chain constant CH1 domain and the first Fc polypeptide, wherein the first Fc polypeptide comprises one hinge region, one human constant CH2 domain and one human CH3 constant domain, wherein the humanized VH domain is fused to the human CH1 domain, that is fused to the human hinge region, that is fused to the human CH2 domain, that is fused to the human CH3 domain in the N-to C-term direction, and wherein the humanized VH domain contains three complementary determining regions (CDRs) having amino acid sequences as set forth in SEQ ID No.: 4, 5 and 6, and wherein the humanized VH domain has an amino acid sequence as set forth in SEQ ID No.: 8; and (iii) a third polypeptide comprising the second human Fc polypeptide, wherein the second human Fc polypeptide comprises one human hinge region, one human constant CH2 domain and one human CH3 constant domain, wherein the human hinge region is fused to the CH2 domain that is fused to the human CH3 domain in the N-to C-term direction, wherein the human hinge region is truncated at the N-terminus. (i) a first polypeptide comprising one humanized light chain variable domain, and one human light chain constant domain, wherein the humanized VL domain is fused to the human CL domain in the N- to C-term direction, and wherein the humanized VL domain contains three complementary determining regions (CDRs) having amino acid sequences as set forth in SEQ ID No.: 1, 2 and 3, and wherein the humanized VL domain has an amino acid sequence as set forth in SEQ ID No.: 7; (ii) a second polypeptide comprising one humanized heavy chain variable domain, one human heavy chain constant CH1 domain and the first Fc polypeptide, wherein the first Fc polypeptide comprises one hinge region, one human constant CH2 domain and one human CH3 constant domain, wherein the humanized VH domain is fused to the human CH1 domain, that is fused to the human hinge region, that is fused to the human CH2 domain, that is fused to the human CH3 domain in the N-to C-term direction, and wherein the humanized VH domain contains three complementary determining regions (CDRs) having amino acid sequences as set forth in SEQ ID No.: 4, 5 and 6, and wherein the humanized VH domain has an amino acid sequence as set forth in SEQ ID No.: 8; and (iii) a third polypeptide comprising the second human Fc polypeptide, wherein the second human Fc polypeptide comprises one human hinge region, one human constant CH2 domain and one human CH3 constant domain, wherein the human hinge region is fused to the CH2 domain that is fused to the human CH3 domain in the N-to C-term direction, wherein the human hinge region is truncated at the N-terminus.