Hydraulic and mass transfer data including pressure drop, liquid holdup, gas- and liquid-side volumetric mass transfer coefficients and interfacial area are measured for Rauschert-Metall-Sattel-Rings (RMSR) 25, 40 and 50. The volumetric gas-and liquid-side mass transfer coefficients are measured using the absorption systems SO2/air-1 M NaOH and O-2/air-water, respectively. The interfacial area is measured by the CO2/air-1 M NaOH absorption system. The data are described by 2- or 3-parameter empirical correlations and, with significantly larger scatter, also by well-known models taken from the literature. The results are compared with those for classical 25 and 50 mm metal Pall rings and with the results given by the Norton company for geometrically similar Intalox metal tower packing-packings for which a similar range of applications can be expected. Height equivalent to a theoretical plate (HETP) calculated from the mass transfer characteristics of the RMSR packings are compared with the experimentally measured HETP for the atmospheric distillation of isooctane-toluene, methanol-ethanol and ethanol-water.