Monitoring of environmental conditions of products in Supply Chains is commonly demanded by users in distribution and manufacturing processes. This information is also required by customers and authorities at final stages. Sometimes is difficult to collect this information, but especially when products are mixed within the same pallet. The process of mixing products in pallets is called “picking” and is a usual practice when customers require small quantities of each item. The number of resources used and the amount of mistakes involving this process suppose and important drawback for distribution companies. To tackle this lack of competiveness created, this work proposes a three-levels based RFID System. This system tries to improve the process of identification and monitoring of condition of products by means of passive and active tags, and the necessary RFID readers. The three different RFID components are connected to three different levels which Supply Chain has been divided in. RFID readers are actually in the third level, the highest one, are wirelessly connected using ZigBee networks. GPRS modules are also used here to provided real-time global localization of products (RTLS) in the moment of being accessed by readers.