Better fit means better performance. If your saddle is out of position, you’ll waste energy with every pedal stroke. That was our foremost consideration in creating a secure, low-profile clamp for the Service Course® seatpost that allows the saddle to slide farther back along the rails. This unique design also offers 20 mm of setback and micro-adjustment with downward-facing bolt heads that are accessible even if the saddle shell covers the top of the seatpost.
For high strength, low weight, and efficient use of every gram, the shaft and head not bonded together but are 3D-forged from a single piece of 7075 aluminum. The Service Course seatpost with 20 mm of setback weighs 285 g (350 x 27.2) and is available in 275 and 350 mm lengths and 27.2 and 31.6mm diameters.
http://www.zipp.com/seatposts/service-course-seatpost--20-/#
