Size is M. Unused after purchase. Stored at home. The following is a product description: This ankle support is about 0.6mm thick, yet provides firm compression. It's made of 360-degree stretch material that fits snugly even during intense movements. Because it's thin, it doesn't feel bulky and doesn't hinder movement, and it's designed to fit snugly around the heel. Bending and stretching is comfortable. Size: ・Ankle circumference: 18-21cm How to measure ankle circumference: ・Measure the circumference of your ankle. ・If you fall between two sizes, we recommend the larger size.