Arctic Cubic Convertible 3-Way Shoulder Straps Tankini Swim Dress Top and Bottom Versatile convertible swim dress. It can be converted to a butterfly sleeve dress, a sleeveless dress or a cold off the shoulder sleeve dress. Built-in Bra. Separate swim bottom. Size runs smaller than regular sizing, so please view our Size Chart carefully. Please select the size according to your chest/bust measurement. Please choose the next size up if you are not quite sure about the sizing.