The D-Shaped Carabiner Clips are considered the strongest and durable devices. They are made of high strength aluminum alloy with vigorous wear and tear tolerance. Their design exhibits a flexible screw to manually lock the clasp. They are mostly used for securing gear together, making emergency repairs, or simply to hold large amounts of keys or shopping cards. Most of the mountaineers and hikers make use of this product to lock their ropes in place as they climb uphill. If you are planning for any adventure, be sure to carry your carabiner clips!