Couldn't resist this interesting piece in bay and added in my vintage inventory. The strap even looks pretty old, maybe original, didn't receive it yet - on the way, but which timeline you think it belongs?
Also I estimate, this was done for open face pocket watches to be somehow converted to wristwatches by being hold by the clasps - they are moveable and lock. The presentation photos were done with a regular pocket watch. So now I need to find an open face pocket watch :)