2-56 Black-Oxide C.R. 18-8 Stainless Steel Nylon-Insert Locknuts by X1Tools
X1Tools Black-Oxide Corrosion-Resistant 18-8 Stainless 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.