NASA-approved insulation, adventurer-ready slip-on bootie design. Throwing a pair of the low-ankle Tundra Slip-on Aerogel Booties into your pack turns any snow camping, mountaineering, or backcountry hut trips into a luxurious experience without the extra weight. Each bootie features a compression-resistant PrimaLoft® Outdoor Research Women's Tundra Slip-on Aerogel Booties