The Serfas® Dual Density® line of saddles is constructed using our patented I.C.S. (Infinite Comfort System) technology. Made up of a soft flexible rubber base followed by two layers of soft and firm closed-cell foam, and a final top layer of friction-reducing Reactive Gel® covered in moisture-wicking four-way stretch Silk-Tech Lycra. Features Serfas® Silk-Tech four-way stretch moisture-wicking Lycra cover, Deep Groove™ Design, Dual Density® Progressive Foam Technology, steel rails.