LA Sportiva used a super insulating lightweight PE outsole to keep the weight down and the TPU midsole is excellent for crampon compatibility and stability on steep terrain. * This super lightweight double boot has a PE thermal insulating inner boot that is coupled with a thermo-reflective outer boot with an integrated gaiter. * Kevlar anti-perforation fabric * UV resistant & waterproof * IDEAL TERRIAN: High altitude 8000 meter peaks