Features: Pin interface compatible with standard spacing Arduino Uno, Mega, etc. 3.3V power supply chip (same with the official expansion board power chip CC3000 ). Onboard ESP8266-12 stable industrial grade serial WiFi module, using an enhanced PCB antenna Can switch by DIP switch ESP8266-12 stable industrial grade WiFi module operation mode (such as operating mode and upgrade mode), integrated serial port chip Built-in 5V to 3.3V TTL level converter, Onboard standard pitch leads all interfaces ESP8266-12 stable industrial grade WiFi module Onboard four LED displays the status of ESP8266, namely PWR, DFU, AP, STA Package including: 1pcs ESP8266 ESP-12E UART WIFI Wireless Shield Development Board for Arduino UNO R3