These were the last series that did a purge after the main wash and followed by 2 rinses and then a dry. The Custom and Imperial did the same thing as their big brother the Superba. Also, these dishwashers removed more detergent then the newer series that followed. The 21 series and newer did a purge and final rinse. Another interesting that the 19 and 20 series heated their first fill to 150F (66C) before the first circulation for their Full Cycles.