PRO introduced the Tharsis XC line to complement parent company Shimano's XTR M9050 Di2 drivetrain, and like the rest of the line, the seatpost fully integrates to fit a Di2 battery to give you a clutter free ride. PRO uses durable unidirectional carbon throughout this seatpost, which starts at a weight of around 199g. While it's ideal for cross country racing, it's also strong enough to handle trail riding too. Use the side access, single bolt clamp to make a wide range of adjustments before your ride, or for any quick changes you need to make on the trail. The Tharsis XC is available in zero or 20 degrees of setback, with the option of 27. 2, 30. 9, and 31. 6mm diameters.