Standard Meets DIN6923; Diameter of the washer head: 21.8mm (max); Height of the head: 10mm (max)
Made of 304 stainless steel 18-8 (no coating outside) which is superior to regular steel and any zinc plated fasteners, provides good strength and corrosion resistance in bad environments.
Serrations help grip the material surface for easy installation and provide mild vibration resistance.