This is the warmest pair of booties that you will ever own. The new FlashBomb 7mm boot is redesigned to increase warmth without adding extra weight. E5 flash lining with E5 flash lining tape keep your feet toasty warm while remaining lightweight. A stitchless compression strap, velcro shaft closure, and a super thin sole provide structure and durability without bulk. We added an anti stink treatment to reduce odor caused by bacteria.