Red Heart Fine Crochet Thread is a size 20, 100% mercerized cotton thread. This crochet thread is ideal for home decor items, clothing projects and accessories such as hats and gloves. Size: 20. 100% Mercerized Cotton. 400yds (365m). Recommended Crochet Hook US 10 (1mm). Dyelotted: Although we try to match dyelots , we are not always able to. Care: Machine wash gentle, do not bleach, dry flat. Comes in a variety of colors. Each sold separately. Imported.