The system connector-sternum/under arm adaptor adds stability to slings and harnesses. The quick-attach tri glides thread easily onto a double sling for those photographers wanting a chest strap for added stability and security. It's also great when hiking as an added assurance to keep the harness firmly in place on your shoulders. it can also be used with a utility strap-sling or super Classic sling to further secure your gear under the arm. To maximize freedom of movement with the camera, It is usually recommended to fasten the sling's Uni-Loop connector to an OP/TECH USA quick-release plate (sold separately). this gives a bit of added length to the connection area so that you can get into shooting position without interfering with the system Connector- sternum/under arm adaptor.