ROTOTO 1634 Organic Cotton Slub Crew Socks in Light BlueROTOTO 1634 Organic Cotton Slub Crew Socks. Knitted with a mix of eco friendly organic cotton slub yarn and recycled polyester yarn, the fabric provides both the comfort of cotton and the quick drying properties and durability of polyester. Machine Wash Avoid Tumble Drying, as it may cause shrinkage. Made in Japan ROTOTO Crafted and designed in Japan, RoToTo uses traditional and modern manufacturing techniques, to create the ultimate cool comfort sock