The tightly woven 800 denier nylon foam-backed upper is tough and resists snagging while the upper, lined with durable foam-backed nylon, helps with sturdiness and comfort The stretchable lace system makes these boots easy to get on and off while maintaining a snug fit that keeps snow out even in drifts Additional elements like a removable fleece-lined EVA insole and a ¾" removable polymeric foam liner with 400 gram Thermolite® insole makes this boot ready for the demands of winter The Cresta Shell™ and two-color Utila-Trac™ outsole provides waterproof protection