A final conductor arrangement for an Nb3Sn superconductor wire , comprising - a plurality of mutually abutting subelements (1a; 60a) each comprising Nb and Sn and each being configured hexagonally in external cross section, and - an outer structure which comprises Cu and which surrounds the mutually abutting subelements (1a; 60a), the outer structure being configured to be round in external cross section, where the subelements are each configured with - an Sn-containing core , - an inner matrix which comprises Cu and which surrounds the Sn-containing core , - a region of mutually abutting Nb-containing rod elements , which are each configured hexagonally in external cross section, more particularly where the Nb-containing rod elements are each configured with an Nb-containing core filament and a Cu-containing filament casing , - an outer matrix (7; 61) which comprises Cu and surrounds the region of Nb-containing rod elements ; characterized in that the outer structure is configured with an outer tube which is configured to be round in external cross section and internal cross section, in that between the outer tube and the mutually abutting subelements , one or more filling elements (18a-18c) are arranged which radially to the outside have a round profile for direct or indirect abutment against an inside of the outer tube , and which radially to the inside have a serrated profile for abutment against the mutually abutting subelements (1a; 60a), wherein the one or more filling element(s) (18a-18c) is/are applied to the outer side of the mutually abutting subelements , and the outer tube is applied directly or indirectly to the radially outer round profile of the one or more filling element(s) (18a-18c), and in that the entirety of the filling elements (18a-18c), radially toward the inside, form an approximately circular overall profile. - a plurality of mutually abutting subelements (1a; 60a) each comprising Nb and Sn and each being configured hexagonally in external cross section, and - an outer structure which comprises Cu and which surrounds the mutually abutting subelements (1a; 60a), the outer structure being configured to be round in external cross section, where the subelements are each configured with - an Sn-containing core , - an inner matrix which comprises Cu and which surrounds the Sn-containing core , - a region of mutually abutting Nb-containing rod elements , which are each configured hexagonally in external cross section, more particularly where the Nb-containing rod elements are each configured with an Nb-containing core filament and a Cu-containing filament casing , - an outer matrix (7; 61) which comprises Cu and surrounds the region of Nb-containing rod elements ; in that the outer structure is configured with an outer tube which is configured to be round in external cross section and internal cross section, in that between the outer tube and the mutually abutting subelements , one or more filling elements (18a-18c) are arranged which radially to the outside have a round profile for direct or indirect abutment against an inside of the outer tube , and which radially to the inside have a serrated profile for abutment against the mutually abutting subelements (1a; 60a), wherein the one or more filling element(s) (18a-18c) is/are applied to the outer side of the mutually abutting subelements , and the outer tube is applied directly or indirectly to the radially outer round profile of the one or more filling element(s) (18a-18c), and in that the entirety of the filling elements (18a-18c), radially toward the inside, form an approximately circular overall profile. <EOS>