Silk thread embroidery (in coordinating or contrasting shades, depending on the colourway). The calf circumference is 14 inches.
If that is too small for you, and you are interested, there is a company called Boot Bands that makes an expander to allow for a larger calf. The item "Extremely RARE New In Box John Fluevog SWEETY Black/Purple Leather Boots, Sz 10" is in sale since Saturday, November 27, 2021. This item is in the category "Clothing, Shoes & Accessories\Women\Women's Shoes\Boots".The seller is "violet48x" and is located in Austin, Texas. This item can be shipped worldwide.