At the time of delivery, it is required to meet the requirement of 300 tons per warehouse receipt, and the delivery shall be carried out at an integral multiple of each warehouse receipt. In addition, it must meet the national standard GB/T 1499.2-20 18, and it should be a commodity with a registered trademark produced by a production enterprise registered in this exchange. The reinforcement of each warehouse receipt shall be composed of goods produced by the same manufacturer, with the same brand, registered trademark, same nominal diameter and same length.