Arvid Nilsson 5085206000 external serrated lock washer (fan washer) to DIN 6798 Form A, for M6 bolts, zinc-plated steel. Inner diameter 6.4 mm, outer diameter 11 mm, thickness 0.7 mm. The external teeth bite into the bearing surface to resist loosening under vibration. Manufacturer's own designation: Arvid nilsson 5085206000 D6798A 350HV-EL 6 (6,4x11x0,7) external-tooth serrated washer.