Designed primarily for tighter fitting footwear, versatile Superfeet Blue provide excellent biomechanical support for the widest variety of foot shapes. Ideal for feet with low to medium arches. Made from closed cell foam for lasting performance contours to foot shape. Designed for footwear with removable insoles top cover wicks moisture, reduces blistering, and resists odor. Absorbs shock, stabilizes midfoot, and controls over pronation. Blue: for casual shoes, mountain bike shoes recommended for tighter fitting hiking boots without Gore Tex. Ideal for feet with low to medium arches that cannot tolerate maximum support. Men's U.S. shoe sizes: C 5.5 7 D 7.5 9 E 9.5 11 F 11.5 13 G 13.5 15. Women's U.S. shoe sizes: B 4.5 6 C 6.5 8 D 8.5 10 E 10.5 12. Important note: Superfeet does not recommend this style for use with Gore Tex boots as the support ridges in the bottom of the Blue cap can grind into the Gore Tex boot lining.