Head on this page.
SDXC Backwards Compatibility Configuration
SDXC memory cards can be used only with SDXC host products.
SDXC host products can use SD, SDHC and SDXC memory cards.
SDHC memory cards can be used with SDHC and SDXC host products.
SDHC host products can use both SD and SDHC memory cards.
Backwards capability is a standard, for example a data format in electronics such as video cameras and computers.
A device is backwards compatible if products designed for the new standard can receive, read, view or play older standards and formats.
* Read speed.