The PCB layout has changed for an improvement in WiFi radio performance | 1MB Flash Memory | About program: Please choose "Generic ESP8285 Module" board in Arduino IDE to program it. | Document link: https://nurdspace.nl/ESP8266, video link:https://youtu.be/mS2kQVD5Sxw | What You Get: 1 X ESP8266 esp-01s Module.