Rare earth magnets are the strongest type of permanent magnet currently made. They are amazingly powerful for their size and have innumerable uses. These magnets are 1 inch x 1/2 inch (0.5) x 1/4 inch (0.25) block. They are composed of grade 52 neodymium iron boron magnetic material and are plated in nickel-copper-nickel for a shiny corrosion resistant finish. Their individual pull force is approximately 22.6 lbs.