A "D ring" is a type of metal or plastic fastener shaped like the letter "D." It is commonly used in various applications, including securing items, attaching straps, or organizing gear. D rings are often found in outdoor equipment, such as backpacks and tents, as well as in industrial settings for lifting and rigging. These rings can be attached to a variety of materials, including fabric and leather, and come in different sizes and strengths. They are essential components in products like harnesses, dog collars, and safety equipment, providing a reliable point for connecting and holding items securely.