This thread is a stranded form of GSP which has incredible strength for its size. Advertised as "almost unbreakable", it allows tying techniques never before possible while minimizing thread build-up on small flies. Loosely twisted, it is the only GSP thread that can be split for dubbing loops, although it is fine enough to be doubled for loops without excessive build-up. The white thread takes marker colors easily. This 30 denier thread has a breaking strength of 40 oz. (1.14 kg). 50 meters per spool.