Because the company has a quantity on a purchase order is not the same each time, depending on the item that must be produced now and depending on the availability of a vendor in the delivery of.
Due to the quantity of each order is not the same, depending on the product must be produced at this time, and depending on the availability of males in their delivery.
Because the company has quantity in each order are not equal, depending on the items that need to be made in now and depending on the availability of the seller for delivery.