The MultiMediaCard (MMC) is a memory card standard used for solid-state storage. Unveiled in 1997 by  SanDisk and Siemens AG, it is based on a surface contact low pin-count serial interface using a single memory stack substrate assembly, and is therefore much smaller than earlier systems based on high pin-count parallel interfaces using traditional surface mount assembly such as CompactFlash. Both products were initially introduced using SanDisk NOR-based Flash technology. MMC is about the size of a postage stamp: 24 mm × 32 mm × 1.4 mm. MMC originally used a 1-bit serial interface, but newer versions of the specification allow transfers of 4 or 8 bits at a time. MMC can be used in most devices that can use SD cards.