Bleached, 100% cotton cheesecloth with a 20x12 thread count. This product is qualified to Aerospace Material Specifications 3819 A&B, Class 1 grade, as well as many industrial-specific specifications including: Lockheed Martin P5396-1(A). Douglas Material Specifications 1820, Boeing Material Specifications 15-5F, L-3/Raytheon Part No. 2012. Put-up in Idealfold (accordion) box. 9"x300' folded and 36"x300' when opened. One per case. Sold by the case.