A small, clear ruler with a series of small holes punched in it at regular intervals. "THE "KEYSTONE" COMPASS RULE/Reg No417638/ORMISTON & GLASS/LONDON E.C" is written on the ruler. "C&G/L" is written within a border at the centre of the ruler. The number is marked out in inches "1-6." "FC" has been stamped faintly on the ruler in five places.
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