COMPATIBILITY (IMPORTANT): Only suitable for 38PIN narrow version ESP32 without mounting holes, not suitable for other versions. GPIO 1 INTO 2: This breakout board can expand one GPIO pin of esp32 development board to two, which is convenient for users to reuse all pins in smart home projects. Nice breadboard alternative. 2 TYPE CONNECTIONS: Pin Header & 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 mission. The board of this version has been soldered completely. No need to solder parts by yourself, which is very convenient to use. size: 77 x 63 x 10.5mm Material: plastic colour: Green Package Contents: 1 x ESP32 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.