Non-carbon saddles are typically made with round 7mm rails that fit all standard seat post clamps. Carbon saddles however, are made with an oval rail that measures 7mm wide X 9 mm tall. You will need to purchase a seat post clam that accommodates this 7X9 configuration for your carbon saddle.
There are two different types of seat post clamps that will work.
The first is a clamp that affixes to the top and bottom of the rail, rather than side to side onto the rail. This clamp, which comes standard on many newer bikes, fits both round and oval saddle rails.
The second clamp that will work is a side to side clamp that measures 7mm wide X 9mm tall.
Please make sure to procure one of these types of seat post clamps before you receive your saddle. A traditional side to side 7mm clamp will not work on carbon rails.