The minimum change unit (i.e. a scale) is usually expressed in points, and the monetary form of the minimum change unit can be obtained by multiplying the minimum change unit by the contract multiplier. The minimum change unit has an important influence on the activity of market transactions. If the change unit is too large, it may dampen the enthusiasm of investors. The principle of determining the minimum change unit is mainly to reduce the transaction cost while ensuring the market transaction activity. For example, the minimum change unit of Shanghai and Shenzhen 300 index futures is 0.2 point. Calculated by 300 yuan per point, the lowest price change is equivalent to the 60 yuan of the contract value change.