The Starburst stimulating electrode design incorporates a patented multi-layer gradient pattern providing the most advanced current distribution system available. This unique gradient pattern is made of pure silver, known as a superior conductive material and optimal for stimulating electrodes. The new aloe vera hydrogel has passed rigorous hypoallergenicity testing and provides superior adhesion after multiple uses. Premium 2" Round, 4 per Pack (199657-001) BAL-627, 627SB