From Merrell, the Women's Siren 4 Thermo Mid Zip Waterproof Leather and Knit Booties feature: Waterproof full grain leather and knit upper Waterproof membrane seals out water and lets moisture escape 100% recycled laces and webbing Heavy-duty, Waterproof, YKK medial zipper for easy on and off Bellows tongue keeps out debris Protective and abrasion resistant rubber heel and toe cap 100% recycled fleece lining 200 grams Primaloft® Gold Eco Series synthetic insulation SOLARCORE® Aerogel insole provides underfoot superior warmth while being extremely flexible and ultra-thin 100% recycled mesh footbed cover Cleansport NXT™ treated for natural odor control 5% recycled removable PU footbed FloatPro™ Foam midsole for lightweight comfort that lasts Vibram Icetrek outsole designed to provide the improved grip on very cold, icy, or snowy surfaces Vibram traction lugs specifically designed to increase traction and shed debris with each step Stack Height (heel/toe): 28.5-20.5mm Drop: 8.0mm Lug Depth: 5.0mm Imported.