• built-in USB-UART converter (CH340G)
• 11 digital I/O pins (3,3V)
• 1 analog input
• reset button
• 1 micro USB port for power supply and programming
• DC21 power jack 9-24VDC for additional power supply
• compatible with Arduino IDE development environment
• compatible with NodeMCU environment
• compatible with Wemos D1
• OTA — uploading compiled program code wirelessly over WiFi
• mounting holes Ø3mm

Note! ESP8266EX I/O pins are not 5V tolerant. Only 3.3V-compatible Arduino shields are usable.