Gutermann Elastic Thread is the ideal thread when sewing projects involve gathering, shirring, crimping, and/or smocking. Gutermann Elastic Thread is made from 64% polyester and 36% polyurethane allowing for added elasticity when working with regular sewing projects as well as for welts, knitting projects, and crochet projects. Gutermann Elastic Thread should be used in the bobbin of sewing machines as an under-thread only.