Base Layer Basic. Formerly known as the Heavy Expedition Boot Sock.The Rugged Max Cushion Boot Sock is built for Heavy Expeditions, from summiting Everest to enduring the harshest winter extremes. FITS&'; thickest sock places fine gauge merino wool on the inside of a more durable outer layer, completely enveloping the 'custom-fit-feel&'; of FITS&'; patented knitting structures. This keeps you warmer and drier where you need it in the most extreme conditions. Don&';t mess around. Off road all the way. Hike, Climb, March, Work, MoveEngineered for Whole Foot Comfort Knit with a fine gauge merino wool for temperature regulation and ultimate softness. Wicks moisture, dries fast, and resists odors. Free Range Toe Box ensures room for your toes while contouring around them. Deep Heel Pocket wraps the foot, holds in place, and prevents blisters. Tapered Compression stimulates blood low and keeps the sock from falling down. Enhanced cushioning throughout entire sock.