I have two of these magnets and when I made the mistake of allowing them to come together it literally took all my strength to separate them. The now sit together on the fridge will about four pieces of cardboard separating them. I've had my finger between them and they will leave a mark......
If you've never played with a rare earth magnet they are absolutely nothing like the magnets you are familiar with.
http://www.kjmagnetics.com/proddetail.asp?prod=BX08Y0