McMaster 91286A627 High-Strength Grade 8 Steel Hex Head Screw Zinc-Flake Coated, 3/8"-16 Thread Size, 1" Long PK25

Made from Grade 8 steel, these screws can be used in high-stress applications, such as valves, pumps, motors, and automotive suspension systems. They are at least 25% stronger than medium-strength steel screws. For quick identification, their head is marked with six radial lines. Length is measured from under the head.

Zinc-flake-coated steel screws have a multilayer finish that resists mild chemicals and provides long-term corrosion resistance. These screws are about five times as corrosion resistant as zinc-plated screws, standing up to 720 hours of salt spray per ASTM B117 standards. They also meet ASTM F3393 specifications for appearance and performance. An embedded lubricant makes these screws easier to install than black corrosion-resistant-coated screws. To maintain their corrosion resistance, use them with zinc-flake-coated nuts and washers.

Match the thread spacing of mating components.

Coarse threads are the industry standard; choose these screws if you don’t know the threads per inch.

Screws that meet ASME specifications are made to strict dimensional standards.

Screws that meet SAE specifications comply with testing standards for material quality.