RC Club Frequency Key

When I joined an RC aeroplane club in Australia it was required that you put a key into a special frequency board to let everyone know that you are operating your radio gear on a specific frequency. This prevents other pilots switching on and shooing your model down and you doing it to them.

here is an example: http://www.hooked-on-rc-airplanes.com/rc-frequencies.html

I dont know if this is just for Australia or other places as well.

I could not find where to get the actual key so I co