These new 20-mil Crystal Clear Transparent Covers are specifically designed for organizations that need a premium rigid cover on the front of their report. These covers are slip sheeted with paper to help preserve their crystal clear glossy finish. These 20mil covers are made from an ultra clear formulation of PVC and help to provide extra rigidity and protection to your documents. Use these covers to add quality to your bound documents while allowing the printed title page to show through. These 20mil Mega Heavy Duty Clear Covers can be used with almost any Comb Binding Machine, Coil Binding Machine, Wire Binding Machine, Velobind Machine or Proclick Binding Machine. However, these covers should be punched one at a time and many customers prefer to buy them pre-punched to save time and to help prolong the life of their punch.