Flange - Nyloc Nuts - Flange nuts are used as an alternative to conventional hexagonal nuts in applications where extra bearing is needed. Available with either a plain or serrated metal locking flange base. Nyloc Nuts are a torque prevailing nut, which uses a nylon insert located toward the top of the nut which deforms over the mating thread, capturing the bolt by providing a locking feature resistant to vibration.