Compatible with all Icebug shoes and boots, these floorsavers are easy to put on and take off. You won't want to use your studded shoes indoors without them, as studs damage many flooring materials and are actually slippery on some surfaces. Made of a high grip material blend, the Biosole sole contains 62% FSC certified natural rubber. The following size recommendations apply to boots and ankle high shoes: - Size chart: - US 4 = 36 - 38 - US 6.5 = 39 - 41.5 - US 9 = 42 - 45 - US 11.5 = 45.5 - 47 For Icebug running shoes: choose one option smaller than the previous list recommends. Example: if your shoes are size 44, you shold choose the "US 6.5". 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.