The Antares is 1 of fi’zi:k’s 3 Spine Concept™ Mens Road Saddle shapes.  Of these 3, the Antares shape is wide and slightly curved in profile. The R1’s carbon thermoplastic composite shell and carbon braided rail reduce weight and increase saddle stiffness.   Antares R1 is for The Chameleon: Medium Spine.   If you have an intermediate degree of spinal flexibility (approximately 90 degrees between your straight legs and your back when bending over as far as you can, keeping your legs straight a shoulders’ width apart), you are a chameleon.  Your degree of spinal flexibility helps you so far, before you need to rotate your pelvis slightly to achieve fully the performance position. Fizik Antares R1 Saddle Features Shell: Carbon Thermoplastic Composite with Wing Flex™ for freedom of thigh movement Rail: Carbon Braided 7x9mm Cover: Black Microtex Thigh Glides: Black Microtex Integrated Clip System: Yes Length: 275mm Width: 142mm (regular) / 152mm (large) Weight: 160g (regular) / 165g (large) Product Data Rail Material: Alloy Road: Yes MTB: Yes