If the official back cover is 160, the back cover is 120, the cost is 40. The cost is expensive, the unofficial channel for about 100, the quality is still the official good point, the unofficial quality is not guaranteed, there may be abnormal fever in the change, millet 11 is brittle, it is easy to break, daily use or wear a set, it is estimated that the use of fake gorilla glass, was cheated.