K2 Indy 1 Ski Boots Boys' 21/22 Features and Specifications: FLEX/FEEL: 4/10 EASY ON OFF SHELL MATERIAL: TPU Regrind CUFF MATERIAL: Marfran LINER: CUSHFIT JR- A scaled-down version of our adult Cushfit liner built for our youth boots. OUTSOLE: Alpine DIN (ISO 5355)