This item contains everything you need to make 1 inch refirgerator magnets in our Model m100 ProMaker Button Machine or MultiMaker with 1 inch die set. The shells and collets are made from heavy duty recycled US steel. The mylar is 1.313 inches in diameter, 3 mil thick plastic that protects your graphics and gives the magnets a professional glossy finish. The magnet is a 1/4 inch thick rubber magnet with a peel and stick adhesive that adheres to the inside of the button after it is pressed. It fills the back of the button giving it a solid professional look both front and back. It's strong enough to hold paper to a refrigerator.