| 摘要 |
PROBLEM TO BE SOLVED: To surely prevent a theft by picking while keeping the equipment cost low. SOLUTION: A key opening 30 comprises protruding guide pieces 31 and 32 on a side edge thereof, and a locking tongue piece 20 comprises a lateral groove 25 of a prescribed length guide by the protruding guide pieces and a vertical groove 28 substantially right-angled to the lateral groove on the side surface. The lateral groove 25 is often provided so as to extend from the side surface upper end of the tongue piece 20 to the side surface lower end thereof. The protruding guide pieces provided on the side edge of the key opening are often formed of the first protruding piece 31 for guiding the upper end surface of the lateral groove and the second protruding piece 32 for guiding the lower end of the sliding groove.
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