Metric Nylon Insert Flange Lock Nuts (DIN 6926), Class 8 Zinc

METRIC CLASS 8 NYLON FLANGE LOCKNUT, NON SERRATED, DIN 6926, ZINC CR+3

Metric nylon insert flange lock nuts are basically a metric hex flange nut with a nylon-filled collar at its back end. When a screw reaches the collar, the threads and nylon form a tight, frictional fit, restricting movement of the screw when it's subject to vibration.