A type of fabric, also known as filled-scrim, often used in the construction of a cyclorama, as it has lots of "tooth" to catch light. White, natural, or sky blue.
http://www.rosebrand.com/subcategory156/fabric-by-type-leno-filled-scrim.aspx
http://www.rosebrand.com/subcategory156/fabric-by-type-leno-filled-scrim.aspx