* Progressive taper design improves flexibility and cutting efficiency, especially in tighter or more curved canals 
* Fewer files are needed to achieve a fully tapered canal 
* Made of NiTi alloy and available of hand use

Clinic Key Points: Technology points of the coronal root inserting of root canal preparation. 
* Enlarging the root canal coronal in advance 
* Fixing the working length 
* The preparation of the mid-part of the root canal 
* The preparation of area of the root canal tip 
* Small size file put into root canal to keep the canal unblocked

Use Sequence: 
a. Open the pulp to form a straight line washing channel. 
b. Explore the root canal with #10 and #15 K-files. 
c. Press the root canal to rotate S1 deasil until it cut the dentin and unable to march on, then rotate S1 widdershins to make it deviate from the dentin, repeat this step until up to the deepness of #15 K-files. If necessary, use SX to enlarge the coronal. 
d. Measure and fix the working length with # 15 K- files 
e. Prepare S1 to the working length according to the method referred to step c. 
f. Prepare S2 to he working length 
g. Prepare F1 to the working length 
h. Prepare F2 to the working length ( the minimum recommended dimension) 
i. Choose F3 to get to the working length.