Estone Prototype Shield I/O Extension Board Expansion Module for Arduino Nano V3.0 Draw out all of the digital I/o mouth and analog I/o mouth, every IO mouth has the positive and negative power supply interface standard Lead the I2C interface on the main board, convenient and connection of the I2C device 14 I/O Pin (servo type with GND, power and signal) 8 analog Pin with power output and GND