Heavy-duty magnets work well on file cabinets or metal presentation boards. They are three times stronger than regular magnets. Reusable tub contains 12 small, 12 medium and 6 large magnets in assorted colors (red, yellow, white, blue and green). The small size measures 5/8″ in diameter. Medium magnet size is 1-1/8″ in diameter. Large magnets are 1-1/2″ in diameter.