The Mac Tools 35-piece Master Extractor Set, No. SCEX35S, is used for removing broken bolts. The set comes with six spiral screw extractors and 13 multi-spline screw extractors for removing screws and bolts from 1/4" to 1" in diameter. The multi-spline extractors are designed for high-torque applications, with hex heads for use with sockets or flat wrenches. Combine this with 16 matching left-hand cobalt drill bits for extraction solution on all bolts.