4-40 Adapters | McMaster-Carr

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348 Products

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 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.

Inch-to-Inch Female Hex Thread Adapters

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

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.

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.

Threaded Inserts for Metal

18-8 Stainless Steel Easy-to-Install
Thread-Locking Inserts

Made of 18-8 stainless steel, these inserts have better corrosion resistance than black-phosphate steel.

Black-Phosphate Steel Easy-to-Install
Thread-Locking Inserts

A black-phosphate finish provides mild corrosion resistance.

316 Stainless Steel Easy-to-Install
Thread-Locking Inserts

These inserts are the most corrosion-resistant thread-locking inserts we offer.

Mil. Spec. Stainless Steel Key-Locking Inserts

These inserts are made to stringent military specifications.

Mil. Spec. Alloy Steel Key-Locking Inserts

The strongest key-locking inserts we offer, these inserts are made to stringent military specifications.

Screw-Locking Key-Locking Inserts

Forming the strongest hold of any of our threaded inserts, these inserts have a distorted internal thread to lock screws into place and keys that drive into surrounding material to prevent slipping and rotating.

Steel Round-Base Weld Nuts

A smooth base provides more contact with the mating surface than weld nuts with projections.

Threaded Standoffs

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.