M3 Adapters | McMaster-Carr

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362 Products

Pipe and Pipe Fittings

Miniature Medium-Pressure Stainless
Steel Threaded Pipe Fittings

When space is at a premium choose these compact fittings.

High-Pressure Plated Brass
Threaded Pipe Nipples and Pipe

Typically used with high-pressure brass and bronze threaded pipe fittings.

Miniature Medium-Pressure
Aluminum Threaded Pipe Fittings

Their small size makes these miniature fittings a good choice for cramped, confined spaces.

Right-Angle Flow Rectangular Manifolds

Distribute air or fluid to multiple locations from a single supply source with these manifolds. They are also known as headers.

Low-Profile Hex Manifolds

When you’re short on vertical space, these manifolds are a good fit—they have outlets on the side instead of on top, so they have a lower profile than rectangular manifolds. Use them to distribute air or fluid to five locations from a single supply source.

Tubing and Tube Fittings

Compression Fittings for Stainless Steel Tubing

A single sleeve (ferrule) bites into tubing as you tighten the nut, creating a strong seal. The nut and sleeve are included.

Push-to-Connect Tube Fittings for Air

Nickel-Plated Brass Push-to-Connect
Tube Fittings for Air

Made of nickel-plated brass, these fittings have better corrosion resistance than unplated brass fittings.

Aluminum Low-Pressure Barbed
Tube Fittings for Air and Water

Aluminum fittings have good corrosion resistance, but are lighter in weight than brass.

Nickel-Plated Brass Low-Pressure
Barbed Tube Fittings for Air and Water

The nickel plating on these fittings provides better corrosion resistance than unplated brass fittings.

Choose-a-Color Aluminum Low-Pressure
Barbed Tube Fittings for Air and Water

Color-code fittings for easy identification. These aluminum fittings have good corrosion resistance, but are lighter in weight than brass.

Stainless Steel High-Pressure Barbed
Tube Fittings for Air and Water

Made of stainless steel, these fittings have better corrosion resistance than brass fittings.

Stainless Steel Push-to-Connect
Tube Fittings for Chemicals

Fittings are 316 stainless steel, which has excellent chemical resistance and is more durable than plastic.

Fasteners

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.

Metric-to-Metric Male-Female Hex Thread Adapters

In addition to joining male- and female-threaded parts, these adapters can increase or decrease metric thread sizes and change the thread pitch.

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.

Metric-to-Metric Male Hex Thread Adapters

Twist these adapters onto female metric threads to change pitch or switch thread sizes.

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.

Metric-to-Metric Female Hex Thread Adapters

Increase or decrease metric thread size from one male-threaded part to another. Commonly used to connect two differently sized threaded rods, they have a hex-shaped body, so you can tighten them with a standard wrench.

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.

Easy-to-Install Thread-Locking Insert Assortments

These assortments include various sizes of thread-locking inserts.

18-8 Stainless Steel Key-Locking Inserts

Made of 18-8 stainless steel, these inserts have good corrosion resistance.

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.

Male-Female Threaded Hex Standoffs

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

Metric Steel Hex Weld Nuts

The three weld points on these metric hex nuts create a secure hold on a steel surface.

Metric Stainless Steel Hex Weld Nuts

You can weld these metric nuts to flat and uneven uncoated stainless steel surfaces for a strong permanent hold.