Stopper Plugs | McMaster-Carr

	REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) REACH (Registration, Evaluation, Authorization and Restriction of Chemicals)

REACH Compliant

	DFARS (Defense Acquisition Regulations Supplement) DFARS (Defense Acquisition Regulations Supplement)

DFARS Specialty Metals
COTS-Exempt

DFARS Specialty Metals
Compliant

	Cap Type Cap Type


Push On	Stretchable

Screw On	Adhesive Back

Shrink Fit	Snap On

	Inside Height Inside Height

	Head Diameter Head Diameter

	For Pipe Size For Pipe Size

1/16
1/8
1/4
3/8
1/2
3/4
1
1 1/4
1 1/2
2
2 1/2
3
3 1/2
4
5
6
8
10
12
14
16
18
20

	Flange Diameter Flange Diameter

	For Panel Thickness For Panel Thickness

	Flexibility Flexibility

2,462 Products

Tapered Plugs

Often used as laboratory stoppers, these rubber plugs have good impact and abrasion resistance. They’re tapered to fit a range of hole diameters.

Expandable Tapered Plugs

Place a plug into an opening and tighten the wing nut—the sides expand to create a seal in holes of varying diameters.

Hollow Tapered Plugs

The hollow construction allows these plugs to compress for a snug fit in threaded and unthreaded holes of varying diameters.

Hollow Tapered Plug Assortments

Keep hollow tapered plugs of various sizes on hand to solve whatever problems arise. The hollow construction allows these plugs to compress for a snug fit in threaded and unthreaded holes of varying diameters.

Miniature Tapered Plugs

Sized to fit small openings, these tiny plugs fit snugly but can be removed easily using the flange. Their tapered design fits a range of hole diameters.

Corks

Lightweight and moisture resistant, these plugs are laboratory-grade 100% natural cork. They’re tapered to fit a range of hole diameters.

Pull-Ring Tapered Plugs

Pull the two built-in rings to quickly remove these plugs. All are tapered to fit a range of hole diameters.

Tamper-Evident Tapered Plugs

Often used on gas cylinders, these plugs cinch and lock tightly around valve heads to block the ports—they must be cut off making it clear if the cylinder has been tampered with. The plugs are tapered to fit a range of hole diameters.

High-Temperature Tapered Plugs

Good for electroplating, paint baking, and powder-coating applications, these plugs withstand temperatures up to 570° F. All are tapered to fit a range of hole diameters.

Hollow High-Temperature Tapered Plugs

The hollow construction allows these plugs to compress for a snug fit in threaded and unthreaded holes of varying diameters. Good for electroplating, paint baking, and powder-coating applications, they withstand temperatures up to 450° F.

Expandable High-Temperature Tapered Plugs

Place a plug into an opening and tighten the wing nut—the sides expand to create a seal in holes of varying diameters. Good for paint baking and powder-coating applications, these plugs withstand temperatures up to 450° F.

Miniature High-Temperature Tapered Plugs

Sized to fit small openings, these tiny plugs fit snugly but can be removed easily using the flange. They withstand temperatures up to 470° F, which makes them good for electroplating, paint baking, and powder-coating applications. All are tapered to fit a range of hole diameters.

Chemical-Resistant Tapered Plugs

These plugs have excellent chemical resistance for masking parts during chemical finishing applications such as plating and anodizing. Their tapered design fits a range of hole diameters.

Food Industry Tapered Plugs

Made of FDA listed materials, these plugs are suitable for food contact. They're tapered to fit a range of hole diameters.

Round Plugs

Sealing Plugs

With a compressible flanged top, these plugs are designed to seal the ends of copper tubing often used in water supply lines, refrigerant lines, and HVAC compressors. All are sized to fit standard copper tube dimensions.

Round Plugs

The hollow construction allows these plugs to compress for a snug fit in threaded and unthreaded holes.

Antistatic Round Plugs

Keep equipment safe from electrical currents with these plugs that have a surface resistivity of less than 10¹² ohms.

Conductive Round Plugs

With a surface resistivity of less than 10⁵ ohms, these plugs not only dissipate electrical charges, but can be used as an electrical shield.

Chemical-Resistant Pull-Through Round Plugs

These plugs have excellent chemical resistance for masking parts during chemical finishing applications such as plating and anodizing. Use the smaller end of the plug to pull the larger end into a through hole to form a tight seal.

High-Temperature Pull-Through Round Plugs

Good for electroplating, paint baking, and powder-coating applications, these plugs withstand temperatures up to 600° F. To form a tight seal, use the smaller end of the plug to pull the larger end into a through hole.

Flanged Pull-Through Round Plugs

Designed with a flange, these plugs protect countersunk holes during anodizing, electroplating, paint baking, and powder-coating applications. All withstand temperatures up to 600° F. Use the smaller end of the plug to pull the larger end into a through hole to form a tight seal.

Miniature Pull-Through Round Plugs

Also known as mouse tails, these tiny plugs fit through-hole IDs as small as 0.022”, 0.025", or 0.03”.

Threaded Round Plugs for Straight-Thread Pipe

Seal tube and hose fittings to keep their straight threads protected from contaminants during fabrication and storage.

High-Temperature Round Plugs for NPT Pipe

These plugs withstand temperatures up to 600° F to protect internally threaded NPT connections from contaminants during electropainting, paint baking, and powder coating applications.

Threaded Round Plugs for NPT Pipe

Protect internally threaded NPT connections from contaminants during fabrication and storage.

Threaded Round Plugs for BSPT Pipe

Safeguard internally threaded BSPT connections from contaminants during fabrication and storage.

Threaded Round Plugs for 37° Flared Tube

Designed to fit into 37° flared connections such as those found on JIC and SAE fittings, these plugs protect internally threaded connections from contaminants during fabrication and storage.

Pull-Tab Round Plugs

A time-saving alternative to threaded plugs, these plugs press in place and have an ergonomic pull tab for quick and easy removal. Use them to temporarily protect holes in objects from contaminants during storage, painting, and light fabrication.

Snap-In Round Plugs

Flexible ridges or straps hold these plugs in place and allow them to fit a range of hole diameters.

Square Plugs

Snap-In Square Plugs

Flexible ridges or straps hold these plugs in place.

Push-In Square Plugs

Push these plugs into an opening and friction holds them in place.

Metal Square Plugs

More durable than plastic plugs, these provide the most protection from abrasion and impact. Use them to eliminate sharp edges and create a finished look on metal fence and machine-guard posts. Drive them in place with a hammer for a secure fit.

Domed Square Plugs

Often used on metal furniture, these plugs provide a finished look on posts and tubes. Snap them into place and their flexible ridges will provide a secure grip.

Rectangular Plugs

Snap-In Rectangular Plugs

Flexible ridges securely hold these plugs in place and allow them to fit a range of hole sizes.

Push-In Rectangular Plugs

Push these plugs into an opening and friction holds them in place.

Panel Plugs

Push-In Panel Plugs

Push these plugs into place for a finished appearance on both sides of a panel.

Sealing Panel Plugs

The wings on these plugs expand against the sides of a hole to form a liquid-tight seal. Pierce the plugs with round wire, cable, or tubing and they function as a grommet to create insulated holes.

Locking Panel Plugs

The wings on these plugs expand against the sides of a hole to lock them in place.

Clear Locking Panel Plugs

These plugs are see-through to provide visibility and light transmission. They have wings that expand against the sides of the hole to lock them in place.

Vented Locking Panel Plugs

Vents in the top allow air circulation and permit heat and fumes to escape. All of these plugs have wings that expand against the sides of the hole to lock them in place.

Plastic Snap-In Panel Plugs

Tapered prongs or a snap-in ring securely hold these plugs in place.

Metal Snap-In Panel Plugs

Made of steel, these are our most durable plugs for panels. Tapered prongs snap into the hole to securely hold them in place.

Metal Snap-In Panel Plug Assortments

Keep metal snap-in plugs of various sizes on hand to solve whatever problems arise. Made of steel, these plugs are our most durable plugs for panels. Their tapered prongs snap into holes to securely hold them in place.

Vented Snap-In Panel Plugs

Vents in the top allow air circulation and permit heat and fumes to escape. These plugs have tapered prongs that snap into the hole to securely hold them in place.

Expansion Plugs for Castings

Also known as freeze plugs, these are commonly used to permanently seal the shallow holes left in a component during the casting process.

Fixture Plate Chip Plugs

Keep chips and shavings from clogging or damaging unused holes on fixture plates in milling machines.

Hydraulic Sealing Plugs

Permanently seal unthreaded holes in pneumatic and hydraulic components.

Ethernet Port Plugs

Shield unused RJ45 type ports on computers and other electronic equipment from debris and moisture.

Caps

Chemical-Resistant Round Caps

These caps have excellent chemical resistance for masking parts during chemical finishing applications such as plating and anodizing.

High-Temperature Round Caps

Good for electroplating, paint baking, and powder-coating applications, these caps withstand temperatures up to 440° F or 570° F.

Domed Round Caps

The large domed head extends beyond the diameter of your pipe, rod, or tubing for added protection.

Round Caps

Slide these flexible vinyl caps on and they conform for a snug fit.

Heavy Duty Round Caps

Made of rigid plastic, these caps are more wear resistant than vinyl caps but not as flexible.

Metal Round Caps

More durable than plastic caps, these provide the most protection from abrasion and impact.

Tethered Round Caps

The tethered design allows frequent access to the ends of pipe, tubing, and other round objects without ever misplacing the cap.

Sure-Grip Round Caps

A long, textured pull tab provides a sure grip for quick removal even when wearing gloves.

Roll-Resistant Round Caps

Commonly used on shipping tubes, these caps have a square head to prevent round objects from rolling during shipping and storage.

Hanging Round Caps

Slide these caps over a tool handle or other round object and use the eye to hang it.

Conductive Round Caps

With a surface resistivity of less than 10⁵ ohms, these caps not only dissipate electrical charges, but can be used as an electrical shield.

Antistatic Round Caps

Keep equipment safe from electrical currents with these caps that have a surface resistivity of less than 10¹² ohms.

Food Industry Round Caps

Made of FDA listed materials, these caps are suitable for food contact.

High-Temperature Tapered Caps

Made of silicone, these caps withstand temperatures of 450° F for electroplating, paint-baking, and powder-coating applications. All of these flexible caps are tapered to fit a variety of unthreaded and threaded objects.

Tapered Cap Assortments

Keep tapered caps of various sizes on hand to solve whatever problems arise. These flexible plastic caps are tapered to fit a variety of unthreaded and threaded objects.

Tapered Caps

These flexible plastic caps are tapered to fit a variety of unthreaded and threaded objects.

Heavy Duty Square Caps

Made of rigid plastic, these caps are more wear resistant than vinyl caps but not as flexible.

Heavy Duty Angle Caps

Made of rigid plastic, these caps provide more wear resistance to the ends of angle iron than vinyl caps but are not as flexible.

Corner Caps

Guard the corners of fragile materials such as glass and mirrors.

Rectangular Caps

Slide these flexible vinyl caps onto rectangular objects and they conform for a snug fit.

Angle Caps

Place these flexible vinyl caps over the ends of your angle iron and they conform for a snug fit.

Square Caps

Slide these flexible vinyl caps on and they conform for a snug fit.

Stretchable Sealing Caps

Tug on the pull tabs to stretch these caps onto the tips of bottles, beakers, flasks, and cylinders, creating an airtight seal.

High-Visibility Pull-Tab Caps

A vibrant yellow color makes these caps stand out. They are made of flexible rubber that conforms for a snug fit. Pull the tab for easy removal.

Flexible Pull-Tab Caps

Slide these flexible vinyl caps on and they conform for a snug fit. Pull the tab for easy removal.

Threaded Caps

Protect externally threaded components from contaminants during fabrication and storage.

Squeeze Top Caps

Squeeze the dome top to remove these caps. They're commonly used as thread protectors.

Tear-Tab Caps

Push these caps onto pipe and fittings, then tear their tab to break the seal for easy removal.

Heat-Shrink Round Caps

Permanently seal pipe, tubing, conduit, and even crimped electrical connections. Slide these flexible caps on and use a heat gun to tightly shrink them to the shape of whatever they are covering. Their outer surface shrinks while the inner wall flows into voids to create a sealed connection.

Propane Tank Tear-Tab Caps

Designed for propane tanks such as those on forklifts and grills, these caps protect tank valves during storage and transit. Push the caps onto the valves, then tear their tab to break the seal for easy removal.

DIN Rail Caps

Guard the edges of DIN rail from damage and create a finished look.

Capacitor Caps

Also known as capacitor boots, these caps protect capacitors and wire connections from damage to extend their service life. They also insulate wire terminal connections to help reduce accidental shocks.

Fastener Caps

Threaded Standoff Caps

Give open-ended standoffs a finished look and protect them from dirt and debris.

Screw Caps

Conceal and protect the tops of socket head or button head screws.

Hex Nut Caps

Sized to fit hex nuts, these caps snap on for a tight hold and provide protection from corrosion.

Tamper-Resistant Threaded Standoff Caps

Pin holes on the side of these caps let you insert an installation tool for increased leverage when tightening, making them difficult to remove.

Low-Profile Threaded Standoff Caps

A thin head means these caps sit nearly flush with your surface for a clean look.

Snap-On Fastener Caps

To conceal and protect the entire screw head, insert your screw through the hole in the base and snap on the top.

Hinged Fastener Caps

A one-piece hinged design allows frequent access to screw heads without misplacing the top. To conceal and protect the entire screw head, insert your screw through the hole in the base and flip the hinged top over.

Flange Caps

SAE Flange Caps

Protect SAE hydraulic flanges during shipping, storing, and finishing applications.

Flange Caps

Snap these caps into flange bolt holes to safeguard pipe flanges during shipping, storing, and finishing applications. They all have a thick center pad to protect the flange opening and pipe threads from damage.

Adhesive-Back Flange Caps

Stick these caps on the raised surfaces of flanges or other flat surfaces for extra protection during transport and storage.

Stretchable Flange Caps

Stretch these caps over flared edges such as flanged tubing and valve handles.

USB Caps

Shield USB connectors from damage, contaminants, and moisture when they are not being used.

Rebar Caps

Keep personnel safe from protruding rebar and pipe. Made of rigid plastic, these durable safety caps are bright orange or yellow for excellent visibility.

Fasteners

Surface-Mount Receptacles for Quick-Release Pins

When you can't drill a through hole, use one of these flanged receptacles to provide a permanent, blind hole for a quick-release pin.

Thread-In Receptacles for Quick-Release Pins

Use a screwdriver to install these receptacles in a threaded hole.

Retaining Caps for Quick-Release Pins

Use these retaining caps to secure the ends of quick-release pins in holes that are oversized or out of round.

Push-On Retaining Caps

Use these caps to hold components in place and protect shaft ends.

Chrome-Plated Plugs for Stainless
Steel Socket Head Screws

Insert these plugs into the drive socket to block debris and provide a finished look.

End Caps for Mounting Rods

Hose Fittings

Metal Cam-and-Groove Hose
Couplings for Chemicals and Petroleum

Couplings are metal, which has better durability than plastic cam-and-groove hose couplings. They consist of a plug and a socket that connect and disconnect quickly. Use them if you need frequent access to a line. To connect, insert the plug into the socket and push the levers down.

Metal Garden Hose Fittings

Attach these fittings to garden hose for a variety of water supply applications. They are metal for better durability than plastic garden hose fittings.

Metal Cam-and-Groove Hose Couplings for Water

Metal cam-and-groove couplings have better durability than plastic cam-and-groove couplings.

Threaded Hose Fittings for Compressed Gas

Use these CGA fittings to connect welding hose to pressure regulators and torches.

Dust Caps and Plugs for Snap-Tite H-Shape
Quick-Disconnect Hose Couplings for Hydraulic Fluid

Use these dust caps and plugs to keep contaminants out of your hose line.

Cam-and-Groove Hose Couplings
for Food and Beverage

Couplings are made of FDA listed materials, so they’re suitable for food and beverage applications and won’t impart tastes or odors to the product. They consist of a plug and a socket that connect and disconnect quickly. Use them if you need frequent access to a line. To connect, insert the plug into the socket and push the levers down.

Twist-Claw Hose Couplings for Air and Water

Couplings have an identical claw-style head that connects to another twist-claw hose coupling with a quarter twist.

Threaded Hose Fittings for Hydraulic Fluid

Fittings are threaded on both ends so you can connect them directly to a threaded hose or to pumps, cylinders, and other equipment in your hydraulic system. Use in high-pressure applications up to 6,000 psi

Dust Caps and Plugs for Pioneer Quick-Disconnect
Hose Couplings for Hydraulic Fluid

Use these dust caps and plugs to keep contaminants out of your hose line.

Dust Caps and Plugs for International Standard ISO B
Quick-Disconnect Hose Couplings for Hydraulic Fluid

Use these dust caps and plugs to keep contaminants out of your hose line.

Protective Plastic Plugs for
Cam-and-Groove Hose Sockets for Water

Insert these caps into a cam-and-groove socket to protect the end of the coupling from damage. The attached handle allows you to easily maneuver hose.

Dust Caps and Plugs for International Standard
ISO Minimal-Spill Quick-Disconnect
Hose Couplings for Hydraulic Fluid

Use these dust caps and plugs to keep contaminants out of your hose line.

Plastic Cam-and-Groove Hose
Couplings for Chemicals and Petroleum

Couplings are plastic, which is lighter in weight than metal cam-and-groove hose couplings. They consist of a plug and a socket that connect and disconnect quickly. Use them if you need frequent access to a line. To connect, insert the plug into the socket and push the levers down.

Plastic Cam-and-Groove Hose Couplings for Water

Made of polypropylene, these cam-and-groove couplings are lighter in weight than metal cam-and-groove hose couplings.

Dust Caps and Plugs for International Standard ISO A
Quick-Disconnect Hose Couplings for Hydraulic Fluid

Use these dust caps and plugs to keep contaminants out of your hose line.

Dust Caps and Plugs for Natural
and LP Gas Hose Fittings

To keep contaminants out of your gas line, add these dust caps and plugs to natural and LP gas couplings when they’re not connected. All work with couplings that are rated ANSI Z21.41/CSA 6.9 for use with gas fuel appliances.