These two objects are keepsakes from my time aboard submarines in the US Navy. Officially these are EAB Manifold Covers: little metal and rubber caps that would insert into the female connectors of pressurized air lines that were used to provide vital breathing air in case of an emergency such as a fire which would quickly turn the enclosed air on the submarine toxic and dangerous to breathe. In such cases, rubber & clear plastic masks that covered your entire face with a long rubber hose, called Emergency Air Breathing Masks (EABs for short) would be put on, and you would connect the hose of your mask to one of these air manifolds. Or you could daisy chain off of someone as each mask’s hose also came with its own connector allowing one person to be connected to one of the ports on the manifold and then a second person could connect the first, a third to the second and so on.
During the emergency, these EAB manifold caps were removed to allow people to use the air connections, and the caps would be left to hang from the manifold by their chains until the emergency was over and the caps could be put back on. Part of training and qualifying for subs was learning our submarine so well that we could move around the sub with poor or little vision while wearing an EAB mask. This required taking a deep breath, disconnecting your mask, and then moving through the cramped and cluttered corridors blind while you held your breath until you could reach another air manifold to connect. Once you caught your breath you would repeat the procedure to continue on your course until you reached your destination, which might entail going up & down ladders, through a maze of corridors from one end of the football field long, 3 story moving building to another. Needless to say we spent many long sweaty, and headache inducing hours “sucking rubber” as we called it, standing watch and performing our duties while simultaneously fighting simulated emergencies so we would be ready in case we ever had to do it for real.
So that was the OFFICIAL use for these devices. UNOFFIALLY, and why I happen to have a few, are these were used by I and many if not all of my fellow submariners as key chains… But MORE IMPORTANTLY, as a kind of unofficial symbol of submariner brotherhood — that we all depended on each other and our submarine home’s equipment, like links in a chain. That’s how I saw them anyway. They were a not-so-secret unofficial version of the Dolphins we wore on our uniforms showing we had “qualified submarines” by learning every system on the boat and could be depended on. Even if a submariner was not in uniform, you would know a brother by his key chain.
You couldn’t just swipe one off of an air manifold (I’m sure it happened but you best never be caught doing it). This WAS safety equipment after all that we depended on to keep us from breathing a bunch of dust and garbage the next time we had to suck rubber. So you had to get them from the sailors who maintained them, performing a favor usually in return. Another part of it that fostered brotherhood, (and possibly a bit of cronyism as well.)
The one on the left was the one I actually used. It is an older (and nicer) model made of some kind of copper alloy. It had a nicer rubber gasket too. After YEARS of using it in the Navy and for years after I got out, the rubber had long fallen off and been lost, and eventually the chain itself broke. Despite its condition I kept it as it was my first EAB cover key chain. The other silver-colored (aluminium?) one is one of the newer covers. The rubber is thinner and cheaper it seems, having oxidized and got unbending and brittle early, something the rubber on my old one never did.