M3 TO M20, ZINC PLATED STEEL BLACK PASSIVATED FORM A FLAT THICK WASHERS DIN 125
M20 - 21.0 x 37.0 x 3.0mm. M3 - 3.2 x 7.0 x 0.5mm. Washers are Form A type (standard, thick, most common). Video is just to show shape and colour etc, size of the actual product will depend on your required size.