Prime-Line M16-2.0 Zinc Plated Steel Class 10 Metric All-Metal Lock Nut (5-Pack)

All-metal lock nuts are often used in cases where nylon insert lock nuts may not be practical to use, such as in high heat applications. Deformations in the threading lock the nut in place by increasing friction. They can typically be started by hand, but require a wrench to get the nut into final position. As with standard hex nuts, they are usually used in combination with a washer to help distribute the load (washers not included).