Used for removing damaged bolt, pipe and other.Bent bolt in the threaded hole can also be pulled out without damaging the threaded hole.When the Phillips or flat grooves of the head of a machine screw collapse, even machine screw that was difficult to extract can be easily removed.Even hexagonal bolt with a corner of its head crushed and bolt that is bent in the middle can be removed easily by punching pilot hole.To extract broken bolts and pipes.Used Bolt Screws (mm):4.8 to 6.4Used Pipe Dimension:-Total Length (mm):50Used Drill Pilot Hole Dimension (mm):2.5Tip Diameter (mm):1.8Original Diameter (mm):4.5Compatible Tap Handle:TH-6Spiral type (for right bolt thread only)Medium Carbon Steel (S45C)Cannot be used for hardened bolts or stainless steel bolts.