US sizes The upper is made of a felt mix, and the lower is quality leather. The long medial zipper and the loop on top of the shaft makes the shoes easy to put on. The fleece lining keeps your feet warm. Michelin Wic soles: non-studded, winter soles for grip. - The fleece lining is made fulfilling the Bluesign®-standard's criteria. It's dyed using Solution Dye -technic which uses less water and energy than traditional dying methods. - The insole is made from BloomSport material which consists 20% of bloom algae foam. Note! As opposed to product images, some Icebug shoes have small, colourful dots in the sole material, due to the recycled material used in them.