what is an sd-mmc?
Secure Digital (SD) describes devices that conform to SD standards for non-volatile memory cards. See the SD Association website for more detailed information. Yes. The SD card specification for a memory card is 32 mm by 24 mm by 2.1 mm. You can also use thinner cards, such as MultiMediaCards (MMC). Cards that have a thickness greater than 2.1mm or that have surfaces that exceed 2.1mm should not be used.
SD cards are an extension of MMC memory cards; this means that it's possible to use MMC cards in newer SD devices. It's also possible to use regular SD cards in SDHC and SDXC devices.