Lightweight, the Icebug Gaiter keeps mud, snow and debris out of the shoes with the help of elastic. A major injury risk during winter is that the Achilles tendon gets wet, cold and stiff. Sealing the edge of the shoe, and adding warmth to this area, helps preventing this problem. The gaiter can be used for all Icebug running shoes. There are two sizes. Medium can be used from size 4-9 men's and 5.5-10.5 ladies and large for 9-13 men's.