This chapter explains preparation of root canal system using GT-0.04 pro-files. Step by step explaining practically covering all the possible angles in 8 points, covering, how to start, how the coronal 1/3rd is first prepared, followed by preparation of middle 1/3rd, and finally preparing the apical 1/3rd, how rotary instruments are rotated at 150 to 300 RPM in speed reducing handpiece, when to use NaOCl copious solution and weak solution, what is cleaning circle, why recapitulation (with pre-calculated WL by K-10 hand instrument), after each change of instrumentation is essential, how to remove smear layer, how to polish finished canal is well discussed in 8 points. The recent advancement of use of “Electron-Microscope” in root canal system preparation, its advantages, disadvantages etc. are all described in details along with relevant figures.