The present invention relates to a fixture set which comprises an accessory part (2), and at least one means for fixing the accessory part (2) to a front surface of a wall of a hollow frame (1), through a hole (6) provided through said wall. The fixing means comprises an anchor (5), a bolt (3) screwed into the anchor (5) and a splitter (4) arranged between the head of the bolt (3) and the anchor (5). The anchor is entirely inserted in the hole (6) in the wall and comprises at least two parts (12) which are radially expandable by the splitter (4), when tightening the bolt, to lock the anchor (5) against the back surface of the wall. Both the splitter (4) and the anchor (5) comprise mutually interlockable structures for substantially restricting rotation of the anchor relative to the splitter. Moreover, the accessory part (2), or an intermediate accessory piece arranged between the accessory part and the wall, comprises means for substantially restricting rotation of said splitter (4) relative to the accessory part (2).