Caleb Components offers Toothed Lock Washers (also known as Shakeproof Washers) to DIN6797 Standard.
Both Internal & External available to purchase online.
Our External Shakeproof Washers range from 4mm up to 12mm: https://springfasteners.co.uk/product-category/washers/external-tooth-lock-washers-din-6797/
Our Internal Shakeproof Washers range from 2mm to 12mm: https://springfasteners.co.uk/product-category/washers/internal-tooth-lock-washers-din-6797/