[For ESP8266 ESP-12E]: It is fully compatible with for ESP8266 ESP-12E. [GPIO 1 into 2]: This expansion board can expand one GPIO pin of Development Board to two, which is convenient for users to reuse pins for large-scale smart home projects. [2 Type Connections]: Two connection methods: Pin Header Connector & Screw Terminal. Just select them according to your purpose. [Double-Layer PCB]: The expansion board is a double-layer board. One pin is wired on both sides. Therefore, the circuit is stable and highly reliable, and there be no poor circuit contact and unstable signal transmission. The board of this version has been soldered completely. No need to solder parts by yourself, which is very convenient to use. Colour: Green Material: Plastic Size: 63x63x9mm Package Contents: 2 x ESP8266 Expansion Board 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.