[For M5  inner diameter (d) 4.7×outer diameter (D) 12.0×thickness (t) 1.0]

This washer is built into a small screw, and can be used as a set machine screw (also known as a washer screw or sesm screw). It can prevent the washer from falling off when you remove the screw, reducing the burden on the work when assembling. RoHS 2 compliant product.