This paper describes a new tool for product configuration based upon constraint techniques. The method is implemented in the Beologic Product Configurator salesPLU$. .It has very strong features for the end user; free order of choices, guaranteed fast response times and optimization functions. The method supports an easy maintenance process with a unique consistency check of configuration data. We compare the tool with previously proposed methods like expert systems to show the advantages of this approach. An simple example of car configuration is presented, however the tool is currently being used for complex products like PABX, vending machines, financial services, pumps.