External Lock Washers - #4 - Zinc-Plated - 40/Pkg

This zinc-plated external tooth lock washer prevents fastener loosening through mechanical bite action. The #4 size features external teeth that grip mating surfaces when compressed, creating reliable holding power under vibration and thermal cycling. Split tooth design distributes contact pressure evenly around the washer circumference. Compatible with #4 bolts and screws in automotive, machinery, and equipment assembly applications where thread locking compounds are not suitable.