This is a rather unusual three state button. It appears to be rated 12v and 500mA, this is not a mains device.
I thought this could make for a neat and simple way to have a two-brightness-level torch, click once to turn on low brightness, click again to go to high brightness, and click again to turn off. Just an idea, I'll leave the implementation up to you )
Body is about 12x12mm and including the button is about 10mm high.
There are two variants…
In the initial state, none of the pins are connected to each other, it's totally open circuit.
Then you click the button and the common pin is connected to the one in the diagram marked B
Then you click again and the common pin is connected to both A and C (which are therefore also connected, but only in this state)
Then you click again to go back to nothing being connected.
The middle pin is common. Click once to connect middle to the left pin, click again to connect middle to the right pin, click again to disconnect.
