Teeth on the outside edge of the washer bite into the screw head and joint for a tight grip. Use with fasteners that have heads large enough to make contact with the teeth, such as pan, button, and binding head screws.

The combination of internal and external teeth boosts gripping power to maintain a tight hold and provide more vibration resistance than other tooth lock washers. Use with fasteners that have heads large enough to make contact with the external teeth, such as pan, button, and binding head screws.