Dresselhaus 1668/001/02 12,5 is an external-tooth serrated lock washer to DIN 6798 AZ for M12 bolts, with an inner diameter of 12.5 mm and an outer diameter of 20.5 mm. The teeth bite into the mating surface to resist loosening under vibration on bolted joints. Zinc-plated steel, minimum order and multiple 100 pieces, country of origin Taiwan.