Double Magnet Additional Neodymium Magnet improves the sound pressure level. Magnetic flux density is increased 32% compared to SC-HC30. Copper Short Ring Copper short ring cuts the unwanted magnetic force that negatively influences the voice coil’s movement. Thanks to copper short ring, the movement of speaker diaphragm is more accurate. The distortion, especially in low frequency range, is reduced. (50% reduction in distortion at 100Hz)