From Birkenstock, the Men's Slub Socks feature: Cotton upper  This casual sock is soft and cozy with a high level of skin-friendly cotton. The fit is enhanced by the pliant cuff and flat toe section. The reinforced toe and heel sections offer lasting comfort by boosting durability and providing the feet with optimum protection. high cotton content elasticated, pressure-free cuff cotton/polyamide/spandex (Lycra) machine wash Imported.