The Thudbuster seatpost from Cane Creek is the most effective and versatile suspension seatpost available. Our parallel-link technology provides a clear advantage in traction, comfort and control without sacrificing performance. Available in both Long Travel and Short Travel configurations, with a range of elastomer spring rates, the Thudbuster is tunable to match your weight and riding preference.
THE SCIENCE BEHIND THUDBUSTER
WORKING IN THE DIRECT PATH OF THE NATURAL TRAVEL OF THE REAR WHEEL.
The Thudbuster technology stays in the direct path of the natural travel of the rear wheel. As a bump lifts the back of a bicycle, the rear wheel pushes up and foward into the rider. The Thudbuster works by compressing along the exact opposite path -- down and rearward -- absorbing force at the same rate: The net movement of the saddle is zero. Fully active elastomers provide approximately 1.3 inches (33mm, Short Travel) of customizable suspension.
More information can be found here: http://www.canecreek.com/products/seatposts
The package comes with 2 different strength elastomers.