Retailers are primarily, but not exclusively, interested in using RFID to identify products across their supply chains to improve the accuracy of their stock inventories. Thus far, most retail users of RFID have employed RFID to enable products in retail stores to be accurately identified and counted more quickly and on a more regular basis. Some retailers use RFID to track the shipment of goods from suppliers and within their own organisations. In addition, RFID can be used to monitor the movement of other retail assets such as pallets and delivery crates as well as promotional materials. For the most part, retail users of RFID seek to have the taggant attached to their products when they are manufactured (known as source tagging) as it is typically a more reliable and cost effective method than applying it within the retail supply chain or at a retail store. Retailers will then make use of fixed and handheld readers to identify their stock at various locations, such as in a warehouse, entering the back of a store, and when it is on a store shelf. Key to the use of RFID is a database management system that enables the unique product codes to be associated with any given item. These systems can provide powerful business intelligence such as the location of any given product and its current status (such as sold or unsold).