These little buggers are great for anything you need a strong magnet for! They hold up to a pound, and they come in two different styles: With a hole, or sans hole. The version with a hole is slightly thinner, measuring just under 1/4" thick, while the not-holey version comes in right at 1/4" thick. Perfect for making magnets out of ANYTHING. Great for teachers and students looking to learn about magnets! Or pinching!