Holds left-handed (reverse twist) 3/32 to 1/2 drill bits. Left-handed drill bits are used to remove broken bolts without creating an oversized hole, which would result in having to use a larger bolt to replace the one removed. A left-handed drill bit actually backs out the original broken bolt without damaging the existing threads. Fits Models 500 and 750 only. * Holds left-handed (reverse twist) 3/32 to 1/2 drill bits * Fits Models 500 and 750 only