SIZING INFO: There are four sizes to ensure a perfect fit. SMALL: fitting women size 8 and below. MEDIUM: fitting women 8.5 to 10.5 and men 7 to 10. LARGE: fitting women 11 and larger and men 10.5 to 13. X-LARGE: fitting men 13.5 to 17. The sizing listed above is appropriate for most shoes and bulky work boots. Please call our office if you would like assistance selecting the proper size. The material used on the upper portion of the shoe cover is a sturdy nylon with a permanent interior finish that will contain any moisture or dirt on your shoes. This same fabric is used to manufacture such items as luggage and tarps. The black soles are made from a durable, gripping material that are extremely non-skid.