Regular S-Lon is the same size as most generic #18 sized nylon at approximately 0.5 mm in diameter and a breaking strength of 34 pounds. It can fit size 8 and larger seed beads. We love it for micro macrame, kumihimo, and all kinds of knotting and stringing projects.
Super-lon by The Beadsmith is a 3-ply twisted, bonded nylon beading cord that is extremely durable and comes in a dazzling array of vibrant colors. We have used this for years and can't get enough of it!