Magnets in guitar pickups can be made up of a few materials. Ceramic magnets are powerful, and have a tight bass and more immediate sound. They are a good choice for heavier music, although other factors in pickup design can influence this as well. Another type of magnet is called Alnico. Short for Aluminum, Nickel and Cobalt, this is the material of more vintage-sounding pickups. The bass is slightly softer, dynamics are emphasized, and there is an overall ‘sweeter’ sound. There are types of Alnico magnets too, from II to IX, named for the varying ratio of materials used. Alnico II magnets have more mids and less bass than, say Alnico V magnets. Higher numbers influence the mids and bass more. Magnets can be cast in different ways, all of which influences the overall tone of the pickup. ‘Aged’ magnets simulate the way magnets lose magnetism over time. Rough-cast magnets will have a rougher surface, which will influence the magnetic pull on the strings.