Price reduced! This is a SEIKO Unique see-through back, skeleton pocket watch that is not listed on Mercari. Original, unmodified see-through back Unique pocket watches are quite rare, aren't they? The movement is also stamped with SEIKOSHA, so it's likely from the 1950s. It might be an Extra Flat or Super movement. The Kelly watch style was likely added later. The strap is damaged but still usable. However, it might crumble, so consider it a bonus. It is currently running, but it hasn't been overhauled, so please assume it needs an overhaul.