outer thimble

例句：

1. 1. The outer thimble of the watch is made of stainless steel.
   手表的外层套环由不锈钢制成。
2. 2. The outer thimble was worn by a fisherman on his fishing boat.
   一位渔夫在渔船上佩戴着外层套环。
3. 3. The outer thimble of the bicycle is designed to protect the chain from wear and tear.
   自行车的外层套环设计用来保护链条免受磨损。