OR designed Brooks Rangers to be the warmest overboots ever made, and their widespread use on expeditions to the coldest places on earth has proven that they have succeeded. They are also the lightest, the most durable, and the most versatile of all overboots. Removable foam insulation and flexible 1000d Cordura rands allow secure attachment of crampon bindings without having to cut holes in the toe and heel, as with neoprene overboots. Gore-Tex uppers trap heat, allow moisture to escape and protect the lower limbs from the elements. Removable Poron footbeds provide great underfoot insulation that will never mash down. The unique instep Cinch-Strap allows you to cinch them down over inner boots or socks for around camp.