XS- Designed for women with a size 2 (US) / 32 (EU) pant size and no larger than a 30 (EU 75) cup.
S- Designed for women with a size 4-6 (US) / 34-36 (EU) pant size and no larger than a 34 (EU 85) cup.
M- Designed for women with a size 6-8 (US) / 36-38 (EU) pant size and no larger than a 36 (EU 90) cup.
L- Designed for women with a 36 (EU 90) cup or larger.
The model in these photos is wearing a size M.