Ritchey Wcs 1-Bolt Cb 27.2X350 0-Sb Ud Seatpost, Zero Offset Ud High modulus carbon fiber Monocoque construction with 3D forged head design Patented SideBinder clamp design uses a single 5mm bolt for quick, secure adjustment Precision forged alloy clamp assembly for strength Low-profile head for optimal saddle clearance and sleek lines Wide saddle clamp reduces stress on lightweight saddle rails Interchangeable clamps provide compatibility for all popular rail sizes Zero offset 157 grams