No.8 gauge Spring Washer (Rectangular) in A2 Stainless
Spring washer designed to help prevent loosening of bolted joints under vibration.
Also know as a Split Lock Washer and a Split Ring Washer.
This type has a rectangular section and is manufactured to ASME B18.21.1-1999.
Where even distribution of load on the mating surface is the primary requirement an alternative spring washer or a flat washer would be a more suitable solution.
In addition Spring Washers do not offer protection for the material being fastened.