Ergonomic city saddle with Core 3D technology is designed to effortlessly follow pelvic movements, reducing pressure on sit bones BASF Infinergy closed cell particle foam core and Orthopedic AirCell Foam padding absorbs road shock and reduces stress on lower back Floating TwinShell design dampens shock before it reaches lower back Forward positioned and anatomically adapted pressure relief channel prevents discomfort and numbness Nylon composite shell Recommended sizing for sit bone width: S/M 912cm, M/L 12-16cm