Selle Italia SLR 3D Carbon L3 Carbon Rails 3D Printed BlackThe proprietary printing pattern and Carbon DLS technology of the SLR 3D Carbon helps make it the lightest 3D printed saddle available The differentiated cushioning zones give progressive absorption and the carbon rails provide strength and ensure comfort on every pedal stroke L3: Wide intertrochanteric distance and high pelvic rotation (Flow and SuperFlow saddles) S3: Narrow intertrochanteric distance and high pelvic rotation (Flow and SuperFlow