Nylon insert lock nuts have a nylon insert. These lock nuts offer excellent vibration resistance. The nylon collar prevents liquid seepage and internal corrosion. Compressive forces grip on the bolt and prevent loosening. Nuts may be reused. Yellow zinc plated fasteners have good corrosion resistant qualities and are a good choice for indoor, outdoor and industrial applications. Grade 8 is high strength for applications requiring superior load and tensile strength such as heavy duty equipment or machinery.