A form of removable memory, MultiMediaCards are available in a range of sizes, including 8, 16, 32, and 64 MB. Like other flash memory cards, they are small (about the size of a postage stamp), durable, and provide solid-state memory and fast read/write speeds. However, they share the higher prices of other kinds of flash memory. MMCs may be gradually supplanted by a form of media called SD, or Secure Digital, memory. However, SD peripherals have backward compatibility, so you will be able to use your existing MMC in a peripheral that accepts SD cards and does not have copy protection requirements.