| 摘要 |
PROBLEM TO BE SOLVED: To provide an extremely convenient and innovative ruler. SOLUTION: A straight line edge 1a is provided to the side edge of a strip sheet-shaped ruler body 1 and a reference line part 2 for indexing the parallel line parallel to the straight line edge 1a is provided to the ruler body 1 at a predetermined position and a fluid 3 is sealed in the fluid housing part 4 provided to the ruler body 1 so as to be visually confirmed wholly or partially from the surface of the ruler body 1 and, when the upper surface 3a of the fluid 3 and the reference line part 2 become parallel to each other or coincide with each other, it can be displayed that the straight line edge 1a is a horizontal state.
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