More Efficient Access With UGREEN Aluminum Card Reader Double Duty Simultaneously read-n-write on two cards to save yourself from constantly plug-n-unplug Wide Compatibility SD Slot: SDXC / SDHC / SD / Extreme I III SD / Ultra II SD / MMC / RS-MMC; TF Slot: Micro SD / Micro SDXC / Micro SDHC / UHS-I Plug and Play No drivers needed for Windows, mac OS, Linux, etc. Just insert and it works Friendly Reminder The data transfer speed could be affected by 2-cards simultaneous reading This USB SD Card Reader could read UHS-II cards at only UHS-I speed. 10X Faster Than USB 2.0 Data transfer speed up to 104M/s (UHS-I, 5Gbps) with USB 3.0 standard, allowing you to transfer HD movies or large files in seconds