At FIRST4MAGNETS we take pride in our range and we supply disc magnets in many sizes and types. Within our range of 15mm (0.59") disc magnets you will find some of our largest ceramic ring magnets ceramic ring magnets are commonly used in loudspeaker systems and larger ceramic ring magnets are also used in magnetic rollers for separating applications and in the printing industry. They are also commonly used in fast running conveyor systems.