4-40 Couplings | McMaster-Carr

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1,002 Products

Coupling Nuts

Low-Strength Steel Coupling Nuts

About half the strength of medium-strength steel coupling nuts, these nuts are for light duty fastening applications.

18-8 Stainless Steel Coupling Nuts

These coupling nuts have good chemical resistance.

Super-Corrosion-Resistant 316
Stainless Steel Coupling Nuts

More corrosion resistant than 18-8 stainless steel coupling nuts, these nuts have excellent resistance to chemicals and salt water.

Brass Coupling Nuts

Brass coupling nuts are corrosion resistant in wet environments and electrically conductive.

Aluminum Coupling Nuts

One-third the weight of steel, aluminum coupling nuts resist corrosion in wet environments.

Plastic Coupling Nuts

Plastic coupling nuts are chemical resistant, nonconductive, and lightweight.

Stainless Steel Extra-Long Coupling Nuts

Stainless steel coupling nuts have excellent corrosion resistance in most environments.

Thread Adapters

Inch-to-Inch Male-Female Hex Thread Adapters

Change thread sizes or types, such as fine to coarse threads, on parts without changing gender.

Inch-to-Metric Male-Female Hex Thread Adapters

Change inch threads to metric with these adapters, or swap metric threads for inch. An external hex lets you tighten or loosen them with a wrench.

Inch-to-Inch Female Hex Thread Adapters

Connect two differently sized male-threaded parts, such as threaded rods, and tighten with a standard wrench.

Left-Hand to Right-Hand
Female Hex Thread Adapters

Often called sleeve nuts, these thread adapters fasten parts with right-hand threads to parts with left-hand threads.

Inch-to-Metric Female Hex Thread Adapters

Adapt threaded rods from inch to metric. These adapters connect two male-threaded fasteners, so you can change the gender of a mating part or increase or decrease its thread size. The hex-shaped body fits into the head of a standard wrench.

Inch-to-Inch Male Hex Thread Adapters

Need to join two female-threaded parts, such as coupling nuts, with dissimilar inch thread sizes? Attach them to these adapters and tighten the exterior hex nut for a secure connection.

Inch-to-Metric Male Hex Thread Adapters

One side inch, one side metric, and a hex in the middle—these handy fasteners connect two female-threaded parts, such as coupling nuts, adapting from inch threads to metric. Tighten with a standard wrench.

Spacers and Standoffs

Female Threaded Hex Standoffs

NAS Female Threaded Hex Standoffs

Choose these standoffs for their adherence to NAS 1831 specifications.

Male-Female Threaded Hex Standoffs

Position components in assemblies, as well as separate or connect parts with these standoffs.

NAS Male-Female Threaded Hex Standoffs

These standoffs are made to NAS specifications.

Thread-Locking Male-Female
Threaded Hex Standoffs

A nylon patch bonded to the threads adds friction, preventing these standoffs from loosening from vibration.

Female Threaded Round Standoffs

Male Threaded Standoffs

Hinged Female Threaded Round Standoffs

Hinged Male-Female Threaded Round Standoffs

Hinged Male Threaded Round Standoffs

Press-Fit Threaded Standoffs with Closed End

Also known as captive standoffs, a recess under the hex clinches the panel for a strong hold that won't push, pull, or twist out. When mounted, the hex sits flush with the surface and the closed end creates a neat, finished appearance.

Press-Fit Threaded Standoffs with Open End

A recess under the hex clinches a panel for a strong hold that won't push, pull, or twist out. When mounted with a lever press, the hex sits flush with the surface and the open end creates a through hole.

Splined Press-Fit Threaded
Standoffs with Open End

Crimp-On Female Threaded Round Standoffs

Often called swage standoffs because you permanently crimp them into a panel.