 Rim impressions from Res-o-Pads are minimal.Unlike standard pads, Res-o-Pads cannot be "floated" into key-cups, as they are sized in 1/32nd-of-an-inch steps (unlike standard saxophone pads which come in 0.5 mm size steps) which may not always correspond closely to key-cup diameters.Though designed to fix into key-cups purely by friction, most saxophone repairers glue them in place using shellac or hot melt adhesive.