| 摘要 |
PROBLEM TO BE SOLVED: To simply change a height of a fence. SOLUTION: A projected part 3a and a recessed part 3b are provided at upper appropriate positions of a fence 3. A sub fence 4 which has a shape capable of fitting to the projected part 3a and the recessed part 3b and can be detached is arranged on an upper part or a side part of the fence 3 and fixed with knob bolts 5.
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