The Selle Royal Scientia Athletic Unisex Bike Saddle utilizes outstanding design based on a Scientific Research. This saddle is designed for ultimate comfort to perfectly fit the Athletic rider. Those riders that have a more aggressive forward position on their bike with an approximate 45@@DG@@ angle where weight is more evenly supported over the entire bike. Padded with the 3D Skin Gel specifically positioned in the Central Reservoir to cushion the soft tissues, this saddle further avoids shocks thanks to the innovative Curva Suspension. Small - for riders with less than 11cm of ischiiation. Medium - for riders with 11-13 cm of ischial variation. Large - for riders with more than 13cm of ischial variation.