| 摘要 |
<p>The bottom of a flat circular hollow element (1) is provided with two hollow circular projections (5) and two curved slots (2). Two flexible strips (3) with a disk-shaped central segment (7) and a pin (4) protruding from the segment (7) are guided through the eyelets at the front of the shoe. The pins (7) are inserted into the hollow projections (5) from below. The shaft of the shoe is tightened when the element (1) is rotated in one direction and the edges pushed apart when the unit (1) is rotated in the opposite direction.</p> |
