This heavy polyester waxed thread is designed for large predator and streamer flies (size 8 and larger hook). It lays flat on the hook and is a 2-strand thread which splits easily for dubbing loops. The heaviest of the Semperfli Classic Waxed Thread series, the 3/0 thread measures 220 denier and has a breaking strength of 39.3 oz. (1,114gm). 120 yards (109m) per spool.