magnet on/off switch

Hey everyone,
I bought a magnetic stand for my dial indicator to use while blueprinting a 
1380 engine. For the life of me, I can't figure out how this magnet works. A 
simple turn of the switch creates a very powerful magnet in the base. Turn 
the switch back and there's no attraction whatsoever. No batteries or 
electricity. This really intrigues me. Can anyone explain how this works?
Mike