You close this bag with a zipper. You can carry it in several different ways, including a detachable shoulder strap.
From Quzo
Port Designs 202322. Case type: Messenger case Maximum screen size: 39.6 cm (15.6") Shoulder strap. Weight: 300 g. Surface coloration: Monochromatic
Amazon
Port Designs Liberty Travel Laptop/Notebook/Chromebook Professional Business Briefcase Sleeve Laptop Bag for 15 inch Windows/Macbook - Black