Ski boot liners typically require both professional thermal boot-fitting and actual days on the hill to form to your foot shape. Not the C.A.S. The dual-density foam booties are anatomically shaped for the right and left foot with punch-outs to accommodate the navicular bone, the first and fifth metatarsal heads, and the ankle and heel bones. They’re also pinched in on the back to follow the natural curve of the Achilles. The result? “From the box to the hill to après—no pain,” one tester says. And great fit also increases power transfer: “I never felt like I was sliding in my boots when initiating a turn on ice or mank,” says another tester who guides in Alaska. And if you have exceptionally weird tootsies, don’t worry: The microcell foam is still heat-moldable. Grind it up to 2mm in problem areas.