Ritchey comp streem vector evo saddlerevolutionary patented vector evo rail increases comfort durability and adjustment range featuresflat profile across the back of the saddle and also flat profile front to back makes the streem a great fit for riders who like to move around on the saddle a lot thin padding profile flat low profile shape with superlight foam profile carbon reinforced thermoplastic rail works with vector wing system to distribute stress and manage shell flex superior compli