Rectangle shaped ceramic blocks is perfect for do-it-yourself projects and making your own magnets. Glue to the back of any light to medium weight item and place on refrigerators, lockers, white boards or any ferrous metal surface. Perfect for home, school and office. Our hard ceramic ferrite magnets are composed of iron oxide and barium or strontium carbonate. Ceramic magnets exhibit relatively good holding strength for their price, making them a popular choice for many consumers, commercial and technical applications.