Specification: Origin: Mainland China Color: Black Green Material: PCB Style: A: Expansion board B: Expansion board+development board PCB material: high-quality FR-4 material PCB layers: 2 layers PCB thickness: 1.6mm Size: About 6.35x6.3x1cm/2.5x2.48x0.39inch Weight: 30g Note: Due to the different monitor and light effect, the actual color of the item might be slightly different from the color showed on the pictures. Thank you! Please allow 1-2cm measuring deviation due to manual measurement. Included: 1 x Expansion board Or 1 x Expansion board 1 x Development board 1. Increased Flexibility: The module is fully compatible with the ESP8266 ESP-12E development board and allows users to expand the GPIO pins of a single board into two, making it extremely convenient for large smart home projects that require the reuse of pins. 2. Versatile Applications: The module is safe and reliable and can be extended to various applications, making it an ideal choice for users seeking flexibility in their designs. 3. Double-Sided Design: The expansion board features a double-sided design with pins on both sides, enabling users to connect multiple devices simultaneously. 4. Superior Stability: With high stability and reliability, the module ensures seamless operation of your project without any disruptions.