M18 × 1.5 mm Hi-Performance Zinc-Plated Steel Nylon-Insert Locknuts by X1Tools
X1Tools Hi-Performance Zinc Plated Steel Nylon-Insert Locknuts / Stop-Nuts are made to resists loosening due to use or vibration without damaging threads thus prevent a fastener from backing off. (Also Known as lock nut, locking nut, self-locking nut, prevailing torque nut, stiff nut or elastic stop nut).