On mine took off the caseback and the gasket sits at the base of the part that protrudes into the case. Picture the caseback like an upside down mushroom and where the stem of the mushroom meets the head, there's a gasket there. I tightened and loctite blue'd the screws so that thing aint coming off. I have a feeling it will be fine
if R's wrists can fit on the deployant of the ROO chrono, and you have similar wrists, then you can fit Diver! Though Id prob wouldnt suggest the bracelet model.
beater Newman on Tropic today
I showered with mine with no problems and that was before I found out mine has the same gap. There is an o-ring between caseback and case. The case back protrudes into the case and there's a gasket around the protruding.
Just get a 21J sub. Personally id spend the extra for atleast an asian clone of the 2824 movement since those cases have sapphire crystals and a smoother beating seconds hand