This looks to be a 1966 (M6) Bulova 666 devil diver watch case, there is no movement, back gasket, crown, ect. just the case as pictured. Doesn't look as if its ever been polished or cleaned. It is very dirty.!  Measured the width as 35.0mm and the length as 43.2mm.  All stainless the bezel does not turn.