K2 Skate Pro Longmount Inline Skates Original K2 Soft boot Using carbon fiber in design is all about keeping the Radical Pro the lightest marathon skate in its class without any sacrifices Built to deliver stability at the highest speeds possible, the Radical frame is an aluminum alloy frame heat-treated for increased stiffness Wheels/Bearings: 100mm, 80a/ILQ-9 Pro Lacing System: Dual Boa Closure System