Each powerful magnetic assembly has a durable nickel-plated cup with mounting hole. Extra strong bases can suspend speakers and spotlights. Add an attachment to center hole to hold lights, tools, plants and more to steel surfaces. Also useful for P.O.P. displays and in-store signage. 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.