This is the Park Tool TWS-3C Torx Compatible 3-Way Hex Wrench. The TWS-3 is a star-shaped Torx(R) compatible 3-way wrench. T10, T25 and T30 wrench sizes in our classic three-way "Y" design. Useful for disc rotor bolts (T25), chainring bolts (T30), and hydraulic brake work (T10).
