Appears to be a size 10, but unmarked.
39 grams including cardboard tube & label.

Label text:

American Thread Co.
The Famous Puritan Star Spangled Crochet Cotton with non-tarnishing metallic yarn

Used for hats, bags, chairbacks, doilies and fashion accessories.
American Thread Co., New York
ART. 40

Buy enough of this color now to complete the article you plan to make. See reverse side for washing instructions.

Washing Instructions:

• Use mild soap suds washing gently in lukewarm water.
• Rinse thoroughly.
• Pin in shape.
• Allow to dry completely.
• Do not iron -- but if iron is used set to “Rayon” (low heat).

Blocking Instructions:

• Pin to size.
• Steam lightly.
• Dry thoroughly.
• Do not iron -- but if iron is used set to “Rayon” (low heat).