The unique MAGMA AMALGAM acoustic guitar strings are wound with two special wires, phosphor bronze alloy and silver plated copper, alternately. This blend of materials perfectly combines to provide players with a great balance between warmth and brilliance and a unique and incomparable sound for all music styles. Thus, this is the best option when you want the mellow tone of the Silver Plated copper wound strings and the projection and volume of the Phosphor Bronze wound strings.