Red Heart Extra Fine Crochet ThreadRed Heart Extra Fine Crochet Thread at discount prices! The perfect crochet cotton for Home decor and accessories. Size: 30. Made of 100% Mercerized Cotton. Put up: 500yd/457m. Recommended Steel Crochet Hook US 12 (0.75mm). Care: Machine wash gentle, no bleach, rinse well and remove promptly, roll in towel, and block. No dye lot.