Also known as Sems screws, these screws have a permanently attached but freely rotating tooth lock washer that bites into the mating surface for vibration resistance.

An O-ring under the head prevents leaks and seals out contaminants.

With a tensile strength of 180,000 psi, these alloy steel screws are among the strongest we carry. They are stronger than Grade 8 steel screws and more than two and a half times stronger than stainless steel screws with split lock washer. The split lock washer helps to resist vibration.

Seal out contaminants and prevent leaks—a silicone O-ring under the head creates a water-, oil-, and chemical-resistant seal.

Made from stainless steel, these metric screws have good chemical resistance and may be mildly magnetic. The washer has sharp internal teeth that 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.

The washer on these screws has 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. 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.

A zinc plating provides mild corrosion resistance.

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.

A rubber O-ring prevents leaks and seals out contaminants. Made from 18-8 stainless steel, these screws have good chemical resistance and may be mildly magnetic.

With a silicone O-ring under the head, these screws prevent leaks and seal out contaminants.

A free-rotating, permanently attached washer distributes holding pressure over a wider area than a flange and remains stationary to prevent scratching the material surface as you tighten the screw.

Made from 18-8 stainless steel, these screws are chemical resistant.

These steel screws are available with corrosion resistant finishes. A rubber-bonded washer compresses to form a watertight seal. They save you time and effort by drilling their own holes and fastening in a single operation.

Made from 410 stainless steel, these screws are strong, wear resistant, and mildly chemical resistant.

The neoprene-backed washer seals out contaminants.

These steel screws are zinc plated to resist corrosion in wet environments.