Although it says "M," I think it would be fine for someone who usually wears S. The lining is on both sides and covers the entire garment, so it's completely opaque even with just one layer. I've worn it a few times and stored it at home. The sleeves have double frills, and there's a covered button at the back. White and navy striped (with white horizontal lines) casual short-sleeved shirt with frill sleeves. - Color: Looks like white and navy stripes - Design: Frill sleeves - Closure: Button closure at the back - Style: Casual, relaxed fit Thank you for looking.