Mutual Screw & Supply

7/8-9 X 3-1/2" Socket Cap Screws | Hex Socket Drive | USA Made | Alloy Steel Thermal Black Oxide (10 / Pkg.)

7/8-9 X 3-1/2" Socket Cap Screws | Hex Socket Drive | USA Made | Alloy Steel - Main image
$51.19 $82.56 In stock

These 7/8-9 x 3-1/2" socket cap screws are manufactured from Alloy Steel Thermal Black Oxide, featuring a hex socket drive. They are well suited to machinery, tooling, jigs, and precision assemblies.

  • Material and finish: Alloy Steel Thermal Black Oxide
  • Drive: Hex Socket Drive
  • Thread size: 7/8-9
  • Length: 3-1/2"
  • Applications: Machinery, tooling, jigs, and precision assemblies

Specifications

  • Product type: Socket Cap Screws
  • Material: Alloy Steel
  • Finish: Thermal Black Oxide
  • Drive type: Hex Socket Drive
  • Thread size: 7/8-9
  • Length: 3-1/2"
  • Threads per inch: 9
  • Measurement type: Inch
  • Pack quantity: 10 per package
Before you pay

Check the method and total at checkout.

When it ships

Allow for processing time as well as the journey to you.

Standard Shipping: Handling (business days) 0–1; Transit (business days) 7–15.

Express Shipping: Handling (business days) 0–1; Transit (business days) 7–15.

View policy
If you need a refund

Keep your order number and contact the store to start.

Please contact us for the refund processing timeframe before returning an item.

View policy
Delivery costs

Review the cost for your destination and chosen service.

Standard Shipping · United States: $0.00

Express Shipping · United States: $3.99

View policy
Returning an item

Check the return conditions before sending anything back.

United States · Return window (days after delivery): 30. Return method: By mail. Return postage: Seller pays.

View policy

Customer Reviews (4.6 / 5 · 5 reviews)

Natalie T. ★★★★★

The black oxide finish on these screws is exactly what I needed for a jig build—it resists rust better than zinc-plated stuff I’ve used before. Hex drive seats cleanly without stripping, even in tight spots. Solid quality for precision assemblies.

Ellie I. ★★★★★

I needed some heavy-duty fasteners for a jig I was building, and these black oxide screws fit the bill perfectly—the threads cut cleanly into the alloy steel without any galling. They’re solid and feel much more robust than the import stuff I’ve used before.

Ella R. ★★★★★

I’ve been using these for jig repairs and they fit perfectly without any wobble—the hex drive really grabs the Allen wrench securely. The alloy steel feels dense and tough, definitely built to last.