 In practice, flash file systems are used only for memory technology devices (MTDs), which are embedded flash memories that do not have a controller.Removable flash memory cards, SSDs, eMMC/eUFS chips and USB flash drives have built-in controllers to perform wear leveling and error correction so use of a specific flash file system does not add any benefit.Multiple chips are often arrayed to achieve higher capacities for use in consumer electronic devices such as multimedia players or GPSs.