Thermally insulated closed-cell foam and thermoreflective aluminum outer boot. Dual-density polyethylene thermal insulating closed-cell foam inner boot. Highly insulated Vibram polyethylene sole with rubber edging platform. * Compatible with step-in crampons. Breathable Cordura and Kevlar gaiter with Riri Storm zipper. Antiperforation gaiter is also UV and water resistant. * 5 mm carbon fiber sole topped with a 2.5 mm polyethylene thermally insulated foam and thermoreflective aluminum layer. Inner boot is slip lasted; Outer boot board lasted. Vibram polyethylene sole with rubber toe inserts.