6/0 Thread, 200 yards, 70 Denier, Waxed. Danville is one of the oldest fly-tying thread companies the U.S. In reference to thread size and strengths, they are used as a standard. All Danville thread is made of nylon. Flymaster. This is a flat fine thread and is also called Danville 6/0. Flymaster is a great thread for smaller flies and where low thread buildup is critical. It is probably the most widely used thread in the world and it is the standard to which other fine threads are compared.