Gently slide the headset onto the head. The reference sensors, which are on the black arm, should make contact with the skin behind the ear. If necessary, gently bend the reference sensor arm so that the sensors make contact with the skin. The frontal sensors should be positioned about three finger widths above the eyebrows. Below are some shots of the placement for Pz, with the three prong gummy slide it back and forth to work the sensors through the hair to make contact with the scalp.