| 摘要 |
A watchcase comprising a case body having a recessed shoulder at the corner of the axially extending inside wall and the bottom thereof, and a back made of hard metal having a longitudinal elasticity modulus larger than 25,000 kg/mm2 and secured to the bottom of the case body. A reinforcement ring having an L-shaped section is secured to the inside wall of the back so that a groove is defined by the outside wall of the reinforcement ring and the inside wall of the recessed shoulder. An O-ring is engaged with the groove for water-tight sealing.
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