The V-neck summer tie-dye dresses you mentioned are made of polyester material. Polyester is a synthetic fabric known for its durability and wrinkle resistance. It is commonly used in clothing because of its lightweight and breathable properties, making it suitable for warm weather. The polyester fabric used in these dresses ensures that they are comfortable on the skin, providing a soft and breathable feel. This can be especially desirable during the summer months when you want to stay cool and comfortable while wearing a dress.