Ideal for a multitude of cool weather activities, such as hiking, camping, and backpacking, the SealSkinz Midweight Mid Length HydroStop Socks offer waterproofbreathable comfort, with additional windproof protection for extra warmth when you're battling the elements. SealSkinz rates these socks with a mid level 35 Thermal Rating, ensuring an ideal blend of heat trapping warmth and high levels of breathability for active use. Its durable nylon and elastane outer fabric surrounds a Hydrophilic membrane for waterproofbreathable comfort on the trail. Additionally, a super warm, incredibly soft merino wool blend along the inside wraps your feet for superior cool weather comfort. Other key features include elasticated ankle straps and instep support for an ultra secure fit without slippage.