FireLine is made of a prewaxed, braided cord consisting of gel-spun polyetholine, known as the strongest fiber, per diameter ever created. It has an unbelievably high tensile strength and has been recommended in numerous how-to articles on beadworking. A good source for beading reference is: http://www.beadingdaily.com/
FireLine works really well for stiffer beadwork or designs with crystals. It is recommended that you use it doubled in projects where the FireLine exits the bead holes at a hard angle, so that the edges of the crystals do not have a chance to abrade the thread. It has no stretch, is waterproof, will not shrink, and remains supple over time.
FireLine will fit a #12 English beading needle, and is stiff enough to use without a needle with many types of beads. It does dull scissor blades, so it is best to designate a pair of scissors to use for cutting Fireline and we recommend Power Pro Scissors for cutting this thread.