G.S.P Thread is by far the strongest thread on the planet for its size / diameter.
(Also known as Dyneema / Power Silk / Nano Thread)
It is constructed by spinning continuous fibers of Gel-Spun Polyethylene, hence the name and is stronger for its weight than steel!
PROS: Extreme strength for its size - excellent for tying deer hair patterns and big saltwater/ pike patterns. ..
CONS: very slippery and expensive compared with polyester threads ... I would not suggest you discard all your traditional threads and use GSP exclusively but it does have its uses. Also, the material does not dye well so be aware that the dye from the darker colours will rub off on your fingers if you whip finish by hand.
Due to the strength of GSP, I would recommend you only use ceramic bobbin holders as the material will cut through metal after regular use. The thread can only be cut effectively when under tension and I would suggest using a craft blade or second best scissors as long term use will blunt your best scissors!