The Specialized CG-R Carbon Seatpost with Zertz Damping comes fitted on the top end Specialized Roubaix & Ruby endurance road bikes. The CG-R seatpost extends the concept that “ Smoother is Faster.” It’s revolutionary post features 18mm of vertical compliance through Zertz vibration damping & FACT carbon construction. No matter what surface your ride takes you on, the CG-R will make it better. Features Revolutionary design allows 18mm of vertical compliance. FACT carbon construction blends durability & comfort. Vibration-damping Zertz for increased comfort. Cylindrical aluminum head assembly adjusts fore-aft & tilt with an easy-access single bolt. Diameter: 27.2mm Length: 350mm