Welcome to the Phil-Lok positive locking fastener web site.   This site has been established to promote the "The Phil-Lok positive-locking fastener", to encourage the practice of "positive-locking fasteners" and to demonstrate the advantages of "positive-locking" over other traditional vibration resistant fastener practices and products available on the market today.  A vibration resistant fastener uses increased frictional forces to prevent nut loosening where a vibration proof (positive-locking) fastener actually uses a physical stop or barrier to prevent nut loosening.  In the case of the Phil-Lok fastener a simple yet unique patented coupling mechanism acts as the physical stop whereby the nut is rotationally fixed relative to the bolt to inhibit rotation of the nut.