Because the power of buyers and sellers is different. The outer disk refers to the selling price transaction list, that is, the seller's price transaction list, which is uniformly included in the outer disk. The inner disk refers to the bidding transaction list, that is, the buyer's price transaction list, which is uniformly included in the inner disk. In layman's terms, the number of orders for upward trading is the outer disk. The number of orders sold is the inner disk.

The key to study the inner and outer disks is to see whether the ups and downs of the inner and outer disks match or deviate from each other. If the external disk keeps rising and the disk keeps rising, this is a cooperative relationship, and the probability of the disk continuing to rise is high. If the external disk keeps increasing, but the disk doesn't rise or fall, it means that the external disk deviates from the disk, and many upward trading orders are at risk of being quilted. Because in practice, the rise and fall of the disk is the fundamental principle.