Please read this description to the end before purchasing. This is a junk item. The calendar does not work. I used it for a few months after purchase, and then stored it. The watch band has been adjusted to fit my wrist, so links have been removed. I will include the removed links and the instruction manual. Regarding the waterproof function, the waterproof packing is likely deteriorated due to aging. Therefore, it may not be usable underwater. Regarding the battery, I replaced it immediately when it ran out. The watch is currently running, but I don't know how long it will last. If the battery runs out, please replace it yourself. If you have any questions, please comment before purchasing. Thank you.