What is original gas escape valve?

Rolex Submariner 300M Gold Oyster Bracelet Automatic Men's Watch Calibre 3135 movement

Most Swiss-style watches with waterproof features are equipped with drain valves, but I believe many of my friends don’t know what it does. So what exactly is a drainage valve? When the diver works in the deep sea, most of the time is in the submarine. The air inside the submarine is a mixture of […]