Black cobweb lycra to run along with yarn to give sock, hat or glove more memory. To use, run the strand of lycra along with a strand of sock yarn. It is advisable to put it from the back of the yarn mast to the front of the yarn mast to keep it from snagging along the way to the knit material. See pictures. If using a Gearhart style mast, it is recommended for use with the lycra extention bar, sold separately on this website.