This is a GU collared shirt. It's an open-collar type. The fabric is relatively thick and sturdy, so it can be worn as a shirt or as a jacket over other clothes. It can be used for three seasons, except for summer. Side slits are present. There is some slight pilling around the armpits. Size: Men's M (Recommended for women as well) Flat measurements: Shoulder width: Approximately 48.5 cm Body width: Approximately 56 cm Length: Approximately 69 cm