Although ARM devices can use normal mechanical disk drives, most use [http://en.wikipedia.org/wiki/Flash_memory flash memory]. Flash memory is non-volatile, consumes little power, and is quite fast for reading, but most types of flash have a limitation of as little as 10,000 write cycles and may be slow for writing. Expandable storage is often provided in the form of [http://www.sdcard.org/home/ SD/SDHC] or microSD /microSDHC cards.