Since the introduction of the Hollow Fiber (HF) Cartridge(TM) at the IDA World Congress in Madrid in October 1997, DuPont Permasep(R) Products commercialized a breakthrough in reverse osmosis (RO) device technology and advanced new membrane products for desalination. The new HF Cartridge(TM) product line has capabilities far beyond the current products. The sum of all improvements further increases the HF device capacity and compactness, and provides new capabilities to operate RO systems more effectively at very high recoveries in a single-stage array with low pressure drop. This paper presents results of field experience on various applications and the results obtained.