This is a very neat and somewhat rare watch and or gauge case.  Back in the day you simply placed your timepiece in the case and strapped it to you wrist and viola, you had a submersible waterproof bottom timer.  This one come complete with a watch and a leather strap.  I would not trust this to be watertight after all these decades, but you never know.

Price $65.00 plus 5.50 shipping