This pressure switch any good?

http://www.asog.net/modules.php?set_albumName=album266&id=abm&op=modload&name=gallery&file=index&include=view_photo.php

I got it from shaim a long time ago and never hooked it up. Its adjustable 0-600. Is it any good and hows it hooked up? It has 3 screws at the top with c,no and nc overtop of them.