lies within the screwdown crown paired with a manual wind movement - there are several Rolex handcrankers with screw down crown that have worked for decades without a problem, so if you are careful to avoid crossthreading the crown and tube you are safe I guess. I think the problem is the "split" case of the Reverso, it has a gap all the way round it along the flank.

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But tbh. how much water resistance do you really need in a sports watch? If it's not water sports I guess that is more than enough. I never had an issue during sporty activity with my Vintage watches with virtually no water resistance at all, as long as the seals can stop the sweat and prevent condensation inside the case you should be fine. When you go swimming that's another case, my minimum requirement is 100m WR and a screw down crown, I somehow don't trust Push-Pull crowns in combination with being submerged in water...