Complex sentence: The more complications in a watch, the more difficult it is to create, assemble and repair: typical date-display chronographs may have 250 parts, while a really complex watch may have a thousand or more parts.
Split into simpler sentences: The more complications in a watch, the more difficult it is to create, assemble and repair. Typical date-display chronographs may have 250 parts, while a really complex watch may have a thousand or more parts.