Details:

Our Shaped Comfort Wool Footbed keeps feet warm and comfortable with a moisture wicking wool felt top surface and light cushioning. Add it to your footwear when the temperature starts to drop.
Size chart:
XS: US 4-4.5
S: 5-6.5
M: US 7-8.5
L: US 9-10.5
XL: US 11-13