Watch
Watch
I remember reading a fiction story about apocalypse scenario when electricity went kaput. Meaning not only a EM blast destroying electrical equipment, but electricity disappearing all together as a physical phenomenon. That's when I though that there are many scenarios in which batteries won't be made or won't be easily accessible. So I figured a fully mechanical watch is needed, either self-winding or hand-winding. Here's a good survival watch, shock-proof, water-proof to 200 meters, self-winding: https://www.amazon.ca/gp/product/B08Q8NRT9T/