Bright Zinc Plated Steel Internal Tooth Shakeproof Washer, M4

RS PRO BZP Spring Steel Lock Washer

From the trusted RS PRO brand, this external tooth lock washer is ideal for added security in fixings and fastenings. They function in the same way as a standard washer, by distributing the load of a bolt against a surface material, but have a locking action that prevents turning of the fastener, meaning there is less chance of the fixing loosening over time or under repeated stress. As such they are commonly used wherever vibration is a factor.