Be sure you're at the top of your game the next time you hit the Nordic trails with the Alpina CSK Skate Boot. Designed for everything from high-end racing to intense training, the CSK has a stiff, powerful flex coupled with a plastic heel counter to keep the boot laterally stiff for a fast and responsive kick and stable glide. A 3D carbon stabilizer and an asymmetric 3D carbon cuff also offer additional support to the ankle and heel area, so you don't wear yourself out by focusing more energy on balancing than moving forward. An anatomic footbed provides killer support and improves balance in all conditions, too, letting you kick hard worry about the burning in your lungs and muscles, not the pain in your arches. The CSK isn't all about performance, though, because its one-piece overboot is backed by a 4Dry membrane to repel moisture and maintain breathability so your feet stay dry from the inside and out. Meanwhile, a light layer of Thinsulate insulation helps to keep feet warm on those colder-than-usual days, without compromising fit, and Alpina also added an elastic calf adjustment feature for a precise and comfortable fit around the ankle. It finished the CSK off with an NNN-compatible Xcelerator sole, so you can step into every NNN-equipped ski in your quiver and make short work of everything from sprint relays to 50K grinds.