The Gator Cases GRB-4U 4U Audio Rack Bag is a portable lightweight rack made from close-grained plywood and covered in padded 600 denier nylon designed to carry 4U-space rack-mountable gear. The threaded rail and zip-out flaps make it easy for the musician on the move. There are strategically designed feet that allow the bag to stand up. There is also a large outside pocket for storing cables or discs. It can be carried by a heavy-duty, adjustable shoulder strap and two padded carrying handles.