Each powerful magnetic assembly has a durable nickel-plated cup with mounting hole. Add a hook or knob to hold lights, tools, plants and more to steel surfaces. More About Ceramic Magnets: 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 consumer, commercial and technical applications. Ceramic magnets have so many practical uses including; craft projects, refrigerator magnets, badge holders, latches, display boards, loudspeakers, security systems, motors, generators & alternators, lifting magnets, brakes, clamps, switches & relays, sweeper magnets, science projects, toys, games, motors, magnetic couplings, POP displays, advertising giveaways, promotional items, novelties & much more.