Performance Posture 3 for pelvic rotation with a balance of comfort and efficiency. Channel Flex on bottom of shell for added compliance. Zone Density shell construction is strategically placed for optimal comfort and performance. Size Specific Curvature ensures each saddle is designed specific to its width. Oversize carbon rails for the ultimate in lightweight strength. inForm BioDynamic products optimize your natural movement for sustained, higher performance. Requires oversize rail-compatible seatpost and 7x10mm seatpost ears.