For example, the KDJ indicator. The traditional way of using it is that when the index reaches 80, it will enter an overbought state; When the index reaches about 20, it enters an oversold state.

Let's take the price increase as an example. When prices continue to rise. The KDJ index will gradually approach 80. Because the calculated value of KDJ index is always between 0 and 100. Then when the index reaches about 80, there is only less than 20 room for further increase. But there is no such price limit.