The “wiichuck adapter” let’s you play with the Wii Nunchuck and other Wii remote peripherals without having to cut cables. Just plug it into the Wii Nunchuck, then into the Arduino, in to Analog In pins 2,3,4,5. Pins 4&5 are the I2C communication pins and Pins 2&3 can act as the power supply for the Nunchuck.