3M&trade, Thinsulate&trade, Insulation Developed by 3M, this innovative microfiber insulation provides a large surface area that traps body heat. & it delivers warmth nearly two times more effectively than down or other synthetic insulations when equal thicknesses are compared. Seam Sealed This technology makes boots practically impenetrable to snow & moisture without adding any extra weight to the footwear. By specially treating our leathers & nylons, then using waterproof tapes & sealants to cover every seam, it&rsquo, s like feet are wrapped in a cocoon. So they stay safe & dry.