Commando Cloth, or Duvetyn (Duvetyne), comes in three weights - 8 oz., 12 oz., and 16 oz., and is a flame retardant 100% cotton fabric with a brushed matte finish used for budget draperies and masking.
The heavy-weight (Commando) version is 98% opaque, and is usually found masking unwanted light or covering an object. It is also used to put a hard edge on light or to create "dots and fingers." Because it is economical, it is often used by filmmakers to cover large objects, such as a tree or even a building, and is most commonly used for window blackouts. No gaffer truck in Hollywood is ever without a roll!
Along with black, it is available in varying colors, widths and weights for a variety of uses.