To use, connect the red wire pin to power on pin 11 (3V) and the other wire (blue or black) to pin 10, the haptic driver pin on the MetaWear. Then connect a 1KOhm resistor in parallel (between pin 10 and 11) For the loudest tones, stay around 4 KHz, but it will work at frequencies between 2KHz and 10KHz. The duty cycle is always 50%.