Drymax Running Lite-Mesh Crew Works better than wool to provide Long Lasting Comfort, Durability and Looks; Made of 73% olefin/11% polyester/11% elastane/5% nylon Prevents blisters with its Anti-Blister System to actively prevent the formation of blisters; Helps the feet and skin stay dry to prevent unwanted blisters. Designed with 3D ADVANCED FIT using special 3D foot models as opposed to the 2D flat form for a more accurate fit; Each sock includes an S, M, L, XL, or XXL color size mark for easy match-up after laundering. Made with multiple air vents that release heat/sweat vapors to keep feet drier & cooler; It works work with built-in vent systems new generation breathable shoes; It comes with dense padding for feet protection without adversely affecting the fit of the shoes. Special fibers ensure a comfortable springiness and do not get stiff, shrink or lose shape over time; Designed to last a long time using the highest quality fibers and abrasion resistant nylon fiber reinforcements.