The SD card reader is a lightweight and compact base device. To connect successfully and begin using it, simply insert the SD card into the SD card reader in the correct direction. Some SD card readers require you to insert the SD card upside down. The device is then connected to another electronic terminal (such as a laptop) to view the files on the SD card.
https://www.apogeeweb.net/electron/what-is-an-sd-card-reader.html