The IFI (Industrial Fastener Institute) has testing standards for ENGLISH and Metric external AND INTERNAL thread LOCKING. For more information, see Industry Spec’s on our web site and view IFI: IFI-124, IFI-524, IFI-524, IFI-525, and IFI-155, IFI-160, IFI-555, and IFI-560.

