Steel hook size 9.

J. & P. Coats “Big Ball” Best Six Cord Mercerized Crochet, Art. A.105, Size 20: 2 balls of No. 1 White or No. 61 Ecru;
or
Clark’s “Big Ball” Mercerized Crochet“, Art. B.34, Size 20: 2 balls of No. 1 White or No. 61 Ecru;
or
Clark’s “Big Ball” Mercerized Crochet, Art. B.345, size 20: 2 balls of No.1 white or No. 61 Ecru.