SD Card Types and Sizes Explained The SD Association classify SD Memory Cards as “removable nonvolatile memory” and specify three types and size for each – the SD Card, the Mini SD Card and the Micro SD Card. Nowadays there are only two main sizes of Secure Digital (SD) Card in general use – the (Full Size) SD Card and the Micro SD Card. Micro SD Cards are often referred to in Asia as TF or Trans Flash Cards, there is…