On-board SD card reader (for card reading via USB) Onboard USB to serial chip (used for wifi configuration via serial port) USB toggle switch (between card reader and serial chip) 3.3V 600mA (used when WIFI module power supply is plugged in USB) Introduction: SD-WIFI is a module that can run ESPwebDev. it into the shape of an SD card so it can be directly inserted into an existing SD card slot and powered. You can connect it to the router using the serial we provided, and then write down the returned IP address. Then, a WebDAV client like can access the file system on the SD card like a cloud disk and allow remote replication / Paste / delete files on SD card. If you have used Flash-Air SD card for , you should understand this method. But Flash-Air cannot be connected to the router because it is running as an AP, and only one device can be connected to it. For example, if your computer is connected to it, you can no longer connect to the Internet at the same time. However, our module is used as a client to access the LAN, and all devices in can access it without affecting the connection. Operating Voltage:3.3V(Via )/5V(Via USB) USB to serial chip:CH340E Max Current:600mA Size:49.5mm x 24mm Color:As Shown Material:PCB Package Contents: 1 * SD-WIFI card module 1 * data cable Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.