Wheels Manufacturing Dropout Savers are designed to replace damaged threads in rear derailleur mounts. Made from aircraft quality steel, dropout savers provide an economical and reliable alternative to the "major surgery" of replacing a complete dropout. - Wide Dropout Saver (DS-1) fits dropouts thicker than 7mm - Narrow Dropout Saver (DS-2) fits dropouts 7mm or less in thickness - 2 pieces per bag