Cannondale Scalpel Alloy front derailleur direct mount adapter.
Both frames (carbon and alloy) utilize a direct mount adapter (i.e. SRAM S3 or Shimano E-Type without a BB plate).
The front derailleur mount adapter installs into the main pivot axle and is specific to a carbon or alloy frame. There is a slight difference between the adapters for the carbon or alloy frames. The front derailleur mounting positions of the carbon adapter are about 2.85 mm lower than the alloy version. This is due to the difference in pivot location between the two different frames. These adapters are not interchangeable between frame types.