The cones of these drivers typically range in size from 6.5 in to 15 in with 10 and 12 in models being the most popular for electric guitar and electric bass combo amps and speaker cabinets. As with all loudspeaker drivers, the magnets are usually made from Alnico, ceramic, or, to reduce weight on more expensive models, neodymium. Higher quality Alnico magnets are reserved for more expensive models. Well-known guitar speaker manufacturers include Jensen, Celestion, Eminence, Electro-Voice, JBL, Peavey, and Vox. Small practice amps often have 6.5  or 8  speakers. Combination (or "combo") amplifier cabinets often have one or more 10 and 12  speakers. The largest speaker "stacks", used in stadium concerts, have eight 10 or 12 in speakers. Bass amplifier speaker cabinets for the bass guitar also often use one or more 10 or 12 in speakers (both 2x10 in and 4x10 in cabinets are popular; in addition, bass cabinets are more likely than electric guitar cabinets to use 15 in speakers.