Foam circles with adhesive backing are used on the forehead or any other hairless areas.  They keep the ECI Electro-Gel from spreading between the electrodes and absorb perspiration.  The disks should be placed on FP1 and FP2 to prevent the cap from moving up on the forehead.  Sponge disks are effectively used on infants due to the tenderness of the scalp and may assist in fitting the caps properly.