4 mm Mild Steel Spring Washer is made from mild steel, which is an alloy made up of iron and carbon. This material is often used in construction and manufacturing due to its strength and durability. Our offered spring washer has a diameter of 4 millimeters, which is quite small. It is likely used for smaller applications where space is limited. 4 mm Mild Steel Spring Washer has a spring-like action, which means it is designed to compress and apply a constant force between two surfaces. This can help prevent loosening and vibration in bolts or screws.