3mm in size. Sold by the yard. Our entire line of Soutache Braid was designed by a textile jewelry artist for textile jewelry artists with attention to consistency of width, thickness and drape so that rayon and polyester braid can be successfully combined.Polyester is an entirely synthetic fiber which takes color beautifully so the polyester braid is available in bright colors. The sheen of polyester is slightly duller than that of the rayon.Rayon is a semi-natural fiber – essentially re-processed cotton. Our rayon braid has more sheen and the colors are available in a more muted palette.