Size 8
if DMC Art. 993, no. 8, 800 grams or a little over 28.5 oz

4” square = 10 mesh by 8.5 rows in filet
Three filet bands crochet joined together.

Challenging

Pattern 15 in Decorative Crochet.
Crochet Decor, p. 8, in 1000 Mailles.