Yeah, I found a few of these too. Not really the right item.
A watts 210 valve shuts off the gas to prevent explosion of the heater and is used in places where it is not practical to drain a T&P like on a slab house with the heater in the center of the place. I often see these with capped off T&P valves and that's VERY dangerous!
Check this out...YouTube - Mythbusters water heater

Very entertaining to watch, just not at my house please. Or one I've inspected.

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