Uni Glo Thread is 3/0 in diameter and is perfect for tying saltwater and streamer fly patterns. It’s strong enough to pull on bead chain and lead eyes and really cinch them down. If you need to bulk up a head you are able to yet using minimal wraps you have any head size you want. The Glo Thread has a nice sheen and will glow in the dark.WARNING: Cancer and Reproductive Harm -www.P65Warnings.ca.gov