In addition to the product line of the Chromolith® RP-18e standard HPLC columns, Merck Millipore now also offers Chromolith® HighResolution RP-18 high-performance columns with end capping in lengths of 50 - 150 mm. Due to the smaller macropores, Chromolith® HighResolution columns provide at least 50% greater efficiency than Chromolith® standard columns and an improved peak shape. At the same time, the counterpressure of the HighResolution columns is still less than half that of a particle column of the same dimensions.