According to the price, the contract can be divided into open contract and closed contract  The opening price refers to the price that can only be determined through calculation according to a certain pricing method, and the closed price refers to the price that has been determined at the time of the conclusion of the contract
A sale contract without a fixed price is an open contract
Company A and Company B sign a supply contract and agree on the unit price of the supply. Company A places the order for the second month to Company B every month, and the settlement is made according to the quantity of Company A's storage at the end of the month. If the price fluctuation of the raw material market exceeds the price of this contract by more than 10%, it can be negotiated again.