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Five chrome carriage bolts round heads square necks 3/8 inch by 3 inches

Zoro Select

Zoro Select MPB758 Carriage Bolt Chrome 3/8-16x3 PK5

SKU CH-YBBS-X64BH

Five chrome-plated Grade 5 carriage bolts with 3/8-16 UNC threads, 3-inch length and square necks for secure wood-to-metal fastening

  • Product typeScrews & Bolts
  • Grade 5 steel rated to 120,000 psi tensile strength
  • Chrome plated finish resists corrosion on exposed threads
  • Square neck locks into wood to prevent bolt rotation
  • UNC coarse threads pair with Grade 2 nuts for secure fit
  • Pack of five 3-inch carriage bolts for multiple installations

Zoro Select MPB758 Carriage Bolts

This pack contains five chrome-plated Grade 5 steel carriage bolts with a 3/8-16 UNC thread and a three-inch length. The square neck design prevents rotation during tightening in wood or metal applications. Each bolt meets ASME B18.5 dimensional standards for consistent fit. The package quantity is five pieces.

Suited for general fastening and wood-to-wood joints

These bolts work well for projects requiring a smooth, rounded head finish and corrosion-resistant chrome plating. They are not intended for high-strength structural connections requiring Grade 8 hardware or metric thread compatibility. Buyers needing stainless steel for marine environments or fine-thread variants should consider other options. The coarse UNC thread limits use in precision adjustment scenarios.

Simple installation with standard tools

A 25/64 inch drill bit clears the shank for the square neck to seat properly in the material. The 13/64 inch head height and 0.782 inch head diameter allow standard socket or wrench engagement. The square neck width of 0.368 inch and height of 0.188 inch require a matching square hole or soft material to lock against rotation. Over-torquing beyond the 120,000 psi tensile rating risks bolt failure.

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Price $17.99
Typical for this category: the median of 2,607 items is $18.99.

Specifications

Product
Brand nameZORO SELECT
Product typeScrews & Bolts

Questions about this item

What size drill bit do I need for the 25/64 in square neck of these carriage bolts?

Use a 25/64 in drill bit to match the square neck dimensions of 0.368 in width and 0.188 in height.

Will these Grade 5 chrome-plated bolts work with the Grade 2 nuts I already have?

Yes, the specifications state they are for use with Grade 2 nuts, and the coarse UNC 3/8-16 threads match standard Grade 2 hex nuts.

How can I confirm the bolts meet the ASME B18.5 standard after installation?

Verify the round head measures 0.782 in diameter and 13/64 in height, and that the square neck seats fully to prevent rotation under torque.

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