Nylon Insert Lock Nuts, also known as Nylock Nuts, are hexagonal nuts that feature a nylon collar inserted into one end. This collar serves as a locking mechanism by gripping the threads of the mating bolt, effectively resisting loosening caused by vibration, shock, or torque.

The nylon insert deforms elastically when the nut is threaded onto a bolt, creating friction and preventing back-off. Because of this feature, these nuts are ideal for applications where a secure hold is essential, such as in automotive, aerospace, and machinery assemblies.

Nylon insert lock nuts are reusable a few times but may lose their locking ability after repeated use or exposure to high temperatures. They are not suitable for high-heat environments, as the nylon can degrade under extreme temperatures.

These nuts are available in various materials including zinc-plated steel, stainless steel (A2-70, A4-80), brass, and more, and conform to both metric and imperial standards like ISO, DIN, and ANSI. They are offered in different thread pitches such as UNC, UNF, and ISO metric.