1BOX Dental Dentsply Rotary ProTaper Files Niti Universal Engine 21MM SX-F3 DESCRIPTION: Description: Big taper rotary nickel titanium endodontic file Model: SX-F3 loaded mixed numbers Length: 21mm Size: pack 6. (1) forming filing three (Sx amber, S1 purple, S2 white): Sx for coronal and root canal shaping short, S1 root canal crown for 1/3 of the preparation, S2 is used in a root canal /