Serrated Washer - External - Metric

Shakeproof washers are an anti-vibration type of locking washer. The surface of the washer features special teeth that lock when tightened, making them resistant to vibration. They are sometimes referred to as lock tooth washers.

On an external shakeproof washer the teeth are found on the outside rim of the washer.

Shakeproof washers are most commonly used in the electrical industry and are often used on larger fasteners where it does not matter so much if the teeth are visible.

The most common thread type in production today. Usually specified as M then a number x another number. This signifies the thread diameter and the length of the fastener.

For example M4 x 30 means that the major thread diameter (the external distance across the outside of the thread) is 4mm and the length is 30mm. Length is usually measured from the underside of the fastener head.