Dropout savers are designed to replace damaged threads in rear derailleur mounts Rather than replacing the dropout at considerable cost & effort, simply follow a few easy steps to repair the existing dropouts Wide Dropout Saver fits dropouts 7mm or more in thickness Narrow Dropout Saver fits dropouts 7mm or less in thickness Contains 2 pieces Starter kit will include: DS-1 (2)pcs, DS-2 (3)pcs, Wheels Mfg.15/32 drill bit (1)pc. Starter Kit