Whitewoods 806-NNNBC Ski Boots (with the ATOP Lacing System) -- The new 806-NNNBC model incorporates the ATOP Lacing System, with the NNN BC Backcountry Touring sole. The ATOP system makes it easy to perfectly tighten or loosen your lace pressure. Turn clockwise click-by-click to tighten, and the reverse way to loosen. The correct lace pressure is an especially important balance between a secure fit and not-too-tight. Any restriction of circulation, may cause cold feet. Other features of the Model 806 NNN include: 200-gram of Thinsulate for added warmth, bellows tongue to keep snow out, padded snow cuff, quick dry velour lining, 4mm insole and breathable weather resistant upper material. NNN BC sole required by any Rottefella BC binding.