One size truly fits all. Fabric is very light weight tee shirt material. Loose fitting comfortable top perfect for travel, cruise, beach wear. The fabric is light weight rayon and spandex that works for all seasons but best for summertime since it is super light weight. Top is poncho style but also has holes for your arms to go through as well. Soft fabric to pair with basic pants, leggings or jeans or simple swimsuit cover up.