Made of multiple strands of incredibly strong yet fine stainless steel cable that is nylon coated; the higher number of strands in the wire, the more flexible and kink-resistant it is. The unique nylon coating provides added kink-resistance and allows light to pass through and reflect off the encased stainless steel wire for a spark of color that makes beaded designs come alive. For Austrian crystals, seed beads and fresh water pearls, use .012 . For medium to heavy glass, metal, ceramic and fiber-optic beads, use .015 to .018 .