Medium-Strength Fastener—Your go-to screws for fastening most machinery and equipment. They have tensile strengths from 90,000 to 120,000 psi.

High-Strength Fastener—Commonly used to fasten components in valves, pumps, motors, and other high-stress applications. These screws have a tensile strength of 125,000 to 160,000 psi.

Low-Strength Fastener—Suitable for light duty applications, such as securing access panels. These screws have a tensile strength of 60,000 psi and lower.

Phosphate-Coated Steel—More corrosion resistant than black-oxide steel, these screws are suitable for environments with some moisture. They have a dark, matte coating for a finished look.

Zinc-Plated Steel—A common choice for areas with occasional exposure to moisture.

Zinc-Yellow-Chromate-Plated Steel—With slightly better corrosion resistance than zinc-plated steel screws, these stand up to more frequent exposure to moisture.

Hot-Dipped Galvanized Steel—The strength of steel with the rust resistance of stainless steel. These screws are an economical alternative to 18-8 stainless steel in wet and outdoor environments, but they won't hold up to salt water and chemicals. The galvanized finish is thicker than other types of coatings, so the threads may be more likely to stick during installation. You can only mate these screws with hot-dipped galvanized nuts.

Zinc-Flake-Coated Steel—The coating is tested to extreme standards, including at least 720 hours of salt spray resistance, to hold up in wet and outdoor environments. An embedded lubricant makes these screws easier to install than corrosion-resistant-coated screws.

Corrosion-Resistant-Coated Steel—A finished appearance plus the rust resistance of stainless steel. The coating has been tested to extreme standards, including 1,000 hours of salt spray resistance, to hold up in wet and outdoor environments.