These corrosion-resistant screws have a washer with sharp internal teeth to keep screws in place during vibration. Unlike external-tooth lock washers, their smooth outside edge provides a finished look and won’t snag on surrounding objects. Also known as Sems screws, the washer rotates freely but is permanently attached. These screws have a moderate height and width profile, offering a middle ground between narrower button heads and wider truss heads. The Phillips drive easily aligns with drivers and withstands more torque than slotted drives, but drivers slip when you apply too much force.

Length is measured from under the head.