HyFlex rotary files are NiTi instruments used for canal enlargement to prepare the root canal for irrigation and obturation in continuous rotation or depending on the clinical situation also in reciprocal motion. The new HyFlex EDM files constitute the 5th generation root canal files. HyFlex EDM NiTi files have completely new properties due to their innovative manufacturing process using electric discharge machining. The files are available in different sizes and have an ISO color coded handle, indicating the tip size of file and color coded rubber stops indicating the degree of the taper (.02 -.08). The new generation of NiTi heat treated files have been manufactured utilizing a unique process that controls the material?s memory, making the files extremely fracture resistant and flexible but without the shape memory of other NiTi files. The files are suitable for multiple use and can be restored during autoclaving. Workpieces are machined in the EDM manufacturing process by generating a potential between the workpiece and the tool. The sparks generated in this process cause the surface of the material to melt and evaporate. This creates the unique surface of the new Niti files and makes the HyFlex EDM files stronger and more fracture resistant. This entirely unique combination of flexibility and fracture resistance makes it possible to reduce the number of files required for cleaning and shaping during root canal treatments without having to compromise preservation of the root canal anatomy. Just like HyFlex CM files, HyFlex EDM files have the already familiar controlled memory effect (CM). This results in very similar properties in terms of material flexibility and regeneration. They are manufactured utilising a unique process in which the crystallographic phase transitions from austenite to martensite at room temperature in contrast to conventional NiTi files, making the files extremely flexible, fracture resistant and able to regenerate multiple times.