The third in Fi'zi:k's animal range of saddles, the Antares R5 is designed for riders of medium flexibility. The Antares' specific shape allows you to shift the muscle groups that you're using by adjusting your postion in the saddle. This is especially convenient on long climbs, where changing your muscle groups means staying fresh longer. Sit back to engage your glutes, or slide forward to let your quads do the work. It's like having two sets of legs. The R5 has a carbon reinforced nylon shell. It incorporates Fi'zi:k's wing flex technology for sit bone support with comfortable, flexible wings that provide pedal efficiency. The rails are made with K:ium: an alloy that's 8% lighter than titanium while maintaining strength and corrosion resistance. The Antares is covered with abrasion resistant Microtex.