The Tecnica Mach 1 100 MV makes a great ski boot for the strong intermediate to expert skier with a medium to narrow forefoot width and medium to narrow leg shape. The Mach 1 is made with the CAS (Custom Adaptive Shape) Shell that has dimples in the most common areas for a bootfitter to customize. These dimples take less pressure to hold a more accurate punch, and make the shell very easy for a bootfitter to work with. Tecnica's CAS UltraFit Liner has Microcell Material in the heel and ankle pockets that can be heated and shaped for a very accurate heel hold. The 35mm Power Strap adds extra rebound as well as keeping a snug wrap across your shin. The Mach 1 100 has the i-Rebound Construction that uses metal on metal connection points that attach the upper cuff to the lower shell that add forward flex resistance, rearward support and added rebound for when you start cranking on the turns. Best Fits a Medium to Narrow Forefoot and Shaft of the Leg, CAS (Custom Adaptive Shape) Shell, CAS UltraFit Liner, i-Rebound, Quick Instep, Actual Flex: 100, Cuff Alignment: Dual, Warranty: One Year, Ski Boot Width: Medium (99-101mm), Flex: Stiff, Used: No, Ski/Walk: No, Forefoot Width: 100mm, Flex Adjustment: No, Buckle Count: 4, Category: Downhill, Ski Gear Intended Use: All Mountain, Instep Height: High, Calf Volume: Standard, Skill Range: Advanced Intermediate - Expert, Model Year: 2019, Product ID: 473825, Model Number: 10178510 255, GTIN: 0888341478968