R-TECH Nylon Insert Locking Nuts, Sizes M3 to M6, Packs of 100 - R-TECH 337221, R-TECH 337221 Nylon Insert Lock Nut M4 Pack Of 100 A range of Steel Hexagonal Nuts with a Nylon locking insert, excellent mechanical strength and a bright zinc-plated, passivated finish for corrosion resistance.Suitable for general use. The nylon insert makes them ideal in applications where vibration or motion could loosen or undo the nut. These Hexagon shaped nuts with nylon insert can be used with a large variety of machine-thread fasteners, including machine screws, bolts, studs, anchors and threaded rods. Typical applications include use in electronic and domestic equipment, general repair and maintenance, circuit board mounting, prototyping, etc. where vibration that could loosen the nuts is a consideration. R-TECH 337221 Nylon Insert Lock Nut M4 Pack Of 100