This item contains everything you need to make 2 inch refirgerator magnets in our Model m200 ProMaker or any US manufactured 2 inch button maker. The shells are made from heavy duty recycled US steel. The backs are black plastic. The mylar is 2.451 inches in diameter, 3 mil thick plastic. The magnet is a 1/4 inch thick, 1 inch square rubber magnet with a peel and stick adhesive that adheres to the back of a button after it is pressed.