Centralized delivery of futures refers to the contract of a futures product in a certain month. After the end of the last trading day, all open trading positions are paired and then concentrated on delivery. Correspondingly, it is rolling delivery, that is, after entering the delivery month and reaching the last trading day, the buyers and sellers can make delivery after matching each trading day until the last trading day. Some varieties of Dalian Commodity Exchange are centralized delivery, while others are rolling delivery. You can check the delivery rules of the exchange on the website of the exchange.