For the 2018 model Cervelo began using their Squoval Max tubeset on the R5. The proprietary seatpost has a flatback design, and is tightened into position by a direct wedge system at the rear, where the seatstays meet the seattube. Cervelo created this Seat Post Clamp Cover For R5 to keep the junction clean and protected. The cover is a stretchy sleeve that attaches around a simple clip that bolts around the more aerodynamic seatpost (which keeps the height position clear if you need to remove the post. Simple, clean and efficient. Cervelo-like, no?