MicroSD / MicroSDHC is a small, removable flash memory card for storing data. Measuring 15 x 11mm with a thickness of just under 1mm, makes them a popular choice for mobile phones, MP3 players, handheld GPS and other compact devices. There are two standards of this card available, SD and SDHC. MicroSDHC (Secure Digital High Capacity) is an extension of the MicroSD standard. A MicroSDHC card is the same physical size as an MicroSD card, make sure your device can accept the HC standard. Classes 2, 4, 6, 8, 10 refer to the data transfer speed in Mbits/s. Adaptors are available to allow a MicroSD card fit into a MiniSD and SD card slot.