Insulation: 3-Layer Merino Wool blend insulation with air mesh & perforated air trap foam. Castle ColdShield Technology: Removable insole engineered from a wool blend with a metallic heat reflecting layer. Waterproofing: Fully integrated Castle DRY-X waterproof membrane. Weatherproof treated shell materials include 1000D nylon upper with Armstrong PU coated leather. Due to the unique layered construction method of these boots, please order actual shoe size. If you are a half size, order down, not up, to achieve proper fit.