Sheet metal tool with apertures designed to fit over a residential gas valve located at the meter typically found on the side of residential homes. The aperture set at a 45 degree angle is used first to move the valve from the vertical position to a 45 degree angle, at which point the tool is flipped over and the in-line aperture is used to continue rotating the valve down into a horizontal position. The horizontal position indicates that the gas line has been closed and no gas will enter the house. The total rotation of the valve is a quarter of a circle (from 12:00 to 3:00).
A sticker on the tool contains instructions for using it, along with an image of the valve for easy identification. The tool should be stored in a location that is easy to remember and access after an earthquake. If stored outside, the tool will continue to work even if rusted, but the sticker may degrade.
See video below from NW Natural for instructions on turning off residential gas.