A guitar speaker cabinet is typically a wooden box that contains one or more guitar speakers. The smallest guitar cabinets have one 6.5" or 8" speaker; these are usually practice amplifier units designed for private practice. Some cabinets designed for rehearsals and small- to mid-size venues contain two 10" or 12" speakers. Another popular format is four 10" or four 12" speakers. Some performers use two 4x10" or 4x12" cabinets. The largest guitar speaker cabinets have eight 10" or 12" speakers. A 4x12" ("four by twelve") is a guitar speaker cabinet containing four 12" speakers. Less commonly, some bass amp cabinets have multiple 8" speakers (e.g., the 8x8" cabinet).