Selle Italia X-Bow SuperflowSaddle rails fixed in rearmost part of saddle limits pressure on ischial bones and perineal areas Shock Absorber system between the shell and rail reduces road shock and vibration 10mm longer rail for more adjustability Superflow cutout reduces physical limitations from prolonged pressure in the perineal area S: 145x255mm, 346g L: 155x255mm, 354g Attributes Gender Unisex Primary Color Black Cut Out Yes Rail Material Alloy Saddle Cover Material Soft