The size is L, but it felt a little tight, so I wore it 2-3 times and then stored it at home for a long time. The tag on the inside of the shirt is wrinkled. Please check the 4th photo. Since it felt a little tight on me, who usually wears L size, I think it would be a perfect fit for someone who usually wears M size. Fluorescent yellow New Balance L size crew neck T-shirt. Shoulder width: 37cm Body width: 42cm Length: 61cm - Brand: New Balance - Size: L - Color: Fluorescent yellow - Design: Crew neck - Material: Polyester Thank you for looking.