Base Layer Basic. The Medium Hiker Crew is based on our most popular ORIGINAL FIT style. Warmer and a bit thicker, it&';s a base layer with strategically-placed FULL cushioning zones and the &';custom-fit-feel&'; of our patented &';Y-Line&'; knitting structures. The ideal choice to balance warmth, cushion, and a slimmer profile and an essential part of any serious gear list. Hike, Run, Walk, Train, Climb, Bike, All Day Patented Whole Foot Comfort Engineering 144N Knit with a fine gauge merino wool for temperature regulation and ultimate softness. Wicks moisture, dries fast, and resists odors. Patented Free Range Toe Box ensures room for your toes while contouring around them. Patented Deep Heel Pocket wraps the foot, holds in place, and prevents blisters. Patented Upright Compression tapers to the leg&';s natural shape, stimulates blood flow, and keeps the sock from falling down. Strategic cushion zones in the heel, toe and arch Material Our materials are crafted to optimize odor resistance, durability, breathability, stretch, and moisture-wicking. Merino Wool 70%, Nylon 22%, Polyester 6%, Lycra 2%