85% minimum acrylic. (There is no indication of what the metallic skein is made from.)

Washing Instructions
Machine Wash
Warm minimum wash (40°C)
Hand Wash
Warm (40°C)
Cold rinse. Short spin. Do not wring.
Do not bleach
Dry clean with all solvents
Do not iron.

From the label:
“We recommend Garter and Moss Stitch”