Synthes ProDisc-C 2.0mm Milling Bit, Synthes 2.0mm Milling Bit HXC, Synthes 2.0mm Milling Bit with 2.35mm x 33.5mm Shaft, and Synthes 2.0mm Milling Bit with Flat Coupling. Spinal surgical instrument: The Synthes ProDisc-C 2.0mm Milling Bits are used as a part of the milling option for keel preparation of the vertebral bodies. The milling bits are coupled to a power tool and interface with the milling guide, which is connected to a trial implant for the keel preparation step.