FireLine is a pre-waxed, braided thread made of extra strong, gel-spun polyethylene. FireLine will provide more structure to your beadwork than standard beading threads. The 4lb test is equivalent to a size AA thread and the 6lb test is equivalent to a size D thread. Both of these will fit a size 10 or 12 needle. Standard scissors will generally not cut FireLine. Fiskars scissors suitable for FireLine can be found here.