The prologo nago evo tri40 is a semi round saddle suitable for medium to long distance riding the new ti rox rails are made from alloy steel this material is highly resistant to traction and torsion and strikes a great balance between lightweight and high strength active density is made up of varying pad densities along the saddle for increased comfort and better pedal strokes key features semi round saddle for medium to long distance riding ti rox rails made from alloy steel activ