| 摘要 |
The present invention makes use of an opening of a latch cover opening to engage the first loose leaf with the second loose leaf at a pivotal opening with a diameter smaller than the opening of the latch cover of the first loose leaf, and the latch cover of the first loose leaf is located between the two axle covers of the second loose leaf after they are coupled. Therefore, the two will not be separated from each other in the front-rear direction easily, so that the first and second loose leaves can be removed and assembled, and fixed securely after the assembling.
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