Sulky 40 wt. is a light weight, but exceptionally strong, silky rayon thread. It is colorfast, both washable and dry cleanable. It is recommended that no bleach or whitening agents be used when laundering. While it is a utilitarian weight that works very well in all decorative applications, it is the preferred thread for "free-motion" machine embroidery as well as computerized embroidery. Most computer embroidery designs are digitized for Sulky 40 wt. Rayon Thread. King Size has 850 yards on the spool. Spool size has 250 yards.