4-40 Screws | McMaster-Carr

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System of Measurement

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Length

Material

Drive Style

Tamper-Resistant Torx

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Head Diameter

Finish

Titanium Carbon Nitride (TiCN) Coated

Zinc Plated

Zinc Yellow-Chromate Plated

Threading

Socket Head Profile

Head Height

Rounded Head Style

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Specifications Met

Flat Head Profile

Drive Size

Thread Type

Tensile Strength

10,000 psi to 19,999 psi

20,000 psi to 29,999 psi

30,000 psi to 99,999 psi

100,000 psi or greater

Screw Size

Thread Direction

Thread Fit

Unified Standard Class 1A

Unified Standard Class 1B

Unified Standard Class 2A

Unified Standard Class 2B

Unified Standard Class 3A

Unified Standard Class 3B

DFARS Specialty Metals

RoHS

Compliant with Exemptions

Not Compliant

REACH

Compliant

Not Compliant

U.S.–Mexico–Canada Agreement (USMCA) Qualifying

Yes

Export Control Classification Number (ECCN)

2,768 Products

Fastening and Joining

Socket Head Screws

With a deeper drive than flat and rounded head screws, these withstand more torque for a tighter hold

327 products

Rounded Head Screws

Sit just above the surface for a low-profile finish and hold tighter than flat head screws

755 products

Flat Head Screws

Fit in countersunk holes for a flush finish that won't snag on surrounding parts

373 products

Hex Head Screws

Used with nuts to create a stronger joint than flat and rounded screws

47 products

Set Screws

Exert pressure at the tip to hold parts in place, unlike screws that hold material together with threads

193 products

Shoulder Screws

Rotate parts around the cylinder under the head to guide and align them during installation

312 products

Thumb Screws

Tighten and loosen by hand without the need for tools

56 products

Tapping Screws

Fasten a range of materials together without needing to tap the hole first

44 products

Captive Panel Screws

Secure panels and enclosures while still having access to them

26 products

Oval Head Screws

The domed top sits slightly above the surface of countersunk holes for a decorative look

21 products

Jack Screws

Create vibration-resistant connections between D-sub cords and panels

22 products

Studs

Press, weld, or screw in place to add a threaded fastening point

17 products

Standoff Caps

Create a finished look on standoffs and protect them from dirt and debris

4 products

Standoffs

Separate, position, or connect components in assemblies

311 products

Thread Adapters

Join threads of a different type, size, and gender

168 products

Threaded Rods

Anchor, connect, or hang components in a wide variety of applications

70 products

Rivet Nuts

Add threads to thin panels with access from only one side; also known as blind inserts

8 products

Weld Nuts

Weld to metal surfaces to add permanent threads

6 products

Measuring and Inspecting

Transfer Punches

Mark the center of an existing hole onto a separate workpiece

1 product

Power Transmission

Lead Screw Collars

Position components and limit travel along a lead screw

3 products

Fabricating and Machining

Fixture Clamps

Secure your workpiece to a fixture table so it won't move during machining

8 products