The straps are adjustable at the back. Very comfortable with a built-in top and padding. The model with brown hair is wearing a 36C and she ordered the large, the model with platinum blonde hair is wearing a 34D and she ordered the small. The model in shorts is wearing the medium top.
 Small = 32 round
 Medium = 34 inches round
 Large = 36 inches around
 XLarge = 38 circumference
 Fabric: 75% Nylon, 25% Spandex