Special ´´Aero´´ Type Exterior Ta Board.Design Studied to Improve Air Penetration and reduces vibrates thanks to its aerodynamic profile.INTENDED USE FOR TRIATHLON AND TIME Trial Bikes.Compatible with All 10/11V Transmissions.Can Be Mounted on All Cranksets (All Brands) with 110mm Spacing, Classic Compact 5 Spoke.100% CNC Made from Aircraft Grade 7075 T6 Aluminum Alloy.For ideal Shifting Quality, We recommend combining it with the syrius 11 inner or the zéphyr inner, with a pitch between 12 and 16 teeth.Also Available in Speed 130 version.Weight:131 Grams.