Mach1 features our most anatomically shaped liner and shell to ensure fit and performance. Available in two distinct shell lasts, Low (LV) and Mid (MV) Volume, Mach1 offers a great fit for a variety of foot shapes. Coupled with the C.A.S. (Custom Adaptive Shape) Liner, and the C.A.S. Shell and Boot Board, this collection offers a precise fit right out-of-the box with additional customization options if needed.