The Double Joint Arm has ball joints on both ends that are locked into position by a single-point tightening mechanism. Each ball joint has a 5/8” pin with a female thread, making it easy to mount and position lights, cameras, monitors, or a wide variety of equipment at any angle. 5/8” pin with female thread. 5/8” pin with female thread. Single-point tightening mechanism locks both ball joints simultaneously. Thanks for purchasing a 9.Solutions product.