The WiiChuck Adapter is a small PCB that is designed to be inserted into the connector of a Nintendo Wii Nunchuck to provide access to all 4 wires of the remote. The power, ground and two-wire interface of the Nunchuck are all broken out to a 4-pin 0.1" pitch header. Compared with standard WiiChuck, the DFRobot WiiChuck has extra 4 pins which allow you connect it to two devices.
The Wii Nunchuck is loaded with features - a 2-axis joystick, two buttons and a 3 axis ±2g accelerometer -- and any device capable of I2C can communicate with it! The WiiChuck allows you to interface with the Nunchuck without making a mess and cutting the wires.