Sharp internal teeth dig into surfaces to resist large amounts of vibration, while the smooth outside edge provides a finished look. Also known as Sems screws, the washer rotates freely but is permanently attached.

Made from stainless steel, these screws have good chemical resistance and may be mildly magnetic. All have a washer with sharp external teeth that dig into surfaces for maximum holding power and vibration resistance. Also known as Sems screws, the washer rotates freely but is permanently attached.

Made from stainless steel, these screws have good chemical resistance and may be mildly magnetic. A curved washer protects delicate surfaces while providing constant tension. Also known as Square Cone Sems screws, the washer rotates freely but is permanently attached.

When compressed, the split lock washer flattens to add tension and prevent loosening from small amounts of vibration. Also known as Sems screws, the washer rotates freely but is permanently attached.

The flat washer distributes holding pressure and protects delicate surfaces from damage while the split lock washer adds tension to prevent loosening from small amounts of vibration.