| 摘要 |
The plug has a tubular body which includes a hollow front portion (2), a long central expandable portion (3) with longitudinal slots (21), and a short rear portion (4). The front and rear portions have internal threads for initial and partial screwing of the threaded fastener. A cup (5) is integrally formed to the hollow front portion, to completely and loosely receive the head of the threaded fastener. The cup has a bottom formed with a fastener hole that allows extension of the fastener through the front portion, and has a diameter greater than the diameter of the tubular body.
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