Forgefix hexagon nut amp nylon insert zp forgefix 100nyloc4 the forgefix nyloc hexagon nut is a fastener that incorporates a nylon component to effectively lock the nut into position on the bolt the nylon component has a smaller inside diameter than the actual nut this locks the nut in place by squeezing the nylon firmly around the bolt when tightened unlike a standard locking washer the nyloc nut prevents the nut from loosening under vibration as the nylon is tightly wedged into the bo