Marine screws are locked in place thanks to their "teeth" (the thread indentations will resist back-out even after prolonged vibration)

3/8 x 5 Powers Round Toggle Bolt Zinc Plated (25)

9/16-18 x 2 1/2 Socket Cap Screw Alloy

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7/16-20 x 3 1/2 L9 Hex Cap Screw Yellow Zinc Plated Domestic USA (300)

7/8-9 x 2 3/4 Grade 5 Hex Cap Screw Plain Domestic USA (60) Nylon Insert Locknuts 18-8 Stainless Steel Marine screws are locked in7 8 9 x 2 3 4 Grade 5 Hex Cap Screw Plain Domestic USA (60). Grade 5 Hex Cap Screws are manufactured in the USA from medium carbon steel. Our Grade 5 material meets or exceeds SAE J429 Grade 5 specifications. All products are manufactured with rolled threads. Typical hardness on diameters 1 4 to 1 inch is HRC 25 34. On diameters over 1 inch to 1 1 2 hardness will range from HRC 19 30. Tensile strength for diameters 1 4 to 1 inch is a minimum of