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Rubber plug Ø21H10

Rubber plug Ø21H10 is designed for circular holes with a diameter of 21 mm and a plug height of 10 mm, used in various industrial, mechanical, electrical cabinet, automotive and interior environments… The product is made from high-quality rubber with good elasticity, excellent sealing capability and long service life.

Effective sealing, waterproof, dustproof, noise reduction & vibration damping.
Heat-resistant, wear-resistant and durable against oils and common chemicals.
Rubber with good elasticity, no cracking and slow aging under continuous working conditions.
Quick install–remove design, compatible with many different drilled hole standards.

Rubber plug

Ø21 H10

Effective sealing · Dustproof · Waterproof

Classification of basic plug types

Various colors & materials

NO.	TYPE	KEY FEATURES	COLORS
01	STANDARD	Domestic plug of higher quality compared with other local products on the market. Made from rubber with general-purpose elasticity, highly waterproof, tolerates short-term outdoor heat, avoid prolonged direct sunlight.	Black White Custom
02	GOOD	Made from natural rubber with high elasticity and excellent waterproof performance.	Black White Custom
03	HIGH-GRADE	Made from high-purity rubber, extremely waterproof, purity close to silicone; elasticity and heat resistance slightly lower than silicone (only a few sizes).	Black White Custom
04	SILICONE	Made from silicone with high elasticity, extremely waterproof and near-absolute purity.	Black White Custom
05	HEAT-RESISTANT	Made from synthetic rubber, chemically stable and heat-resistant over a wide range. Used for insulation and harsh environments.	Black White Custom

Standard technical specifications

Mounting hole diameter

Ø 21 mm

Plug height

H = 10 mm

Material

NR / CR rubber

Hardness

60 ± 5 Shore A

In addition to the standard dimensions and specifications above, we can design and manufacture rubber plugs based on drawings, existing samples, or customized color, hardness and private logo for each application.

Practical applications & benefits of using rubber plug Ø21H10

Common applications

Sealing spare/unused holes on machine bodies, machine bases, electrical cabinet bottoms and junction box covers.
Protecting cut edges and covering drilled holes on steel structures, aluminum frames and plastic components.
Reducing noise and vibration at mounting points on vehicles, conveyors and tanks.
Used in furniture, home appliances and areas that require safe and aesthetically pleasing coverage.

Benefits when choosing this product

Precisely fitted design for high sealing performance, minimizing dust, water and insects entering.
Quality rubber with good elasticity for long-term use without cracking or deformation.
Flexible in color, hardness and order quantity, suitable from small orders to large projects.
Stable production process with consistent dimensions, reducing installation time on production lines.

Guidelines for sizing & storage

Notes when selecting rubber plug size for ceramic pots
During ceramic pot production, uneven shrinkage when firing at high temperature can cause actual drain hole diameters to deviate, especially in diameter. Based on installation surveys and customer feedback, if the pot hole diameter is 21 mm, the suitable plug size should also be 21 mm (taking practical tolerances into account). This ensures a tight fit, no looseness and no leakage.

Recommendation: carefully measure the inner diameter (ID) of the pot hole using a vernier caliper or digital caliper before choosing the plug size.
Storage to increase rubber plug durability
Store in a cool, dry place, away from direct sunlight and temperatures > 40 °C. Do not let the product come into long-term contact with strong chemicals. Occasionally soaking in water, cleaning and letting it dry naturally helps maintain elasticity of the surface and extend service life.

Frequently asked questions about rubber plug Ø21H10

What types of holes can plug Ø21H10 be used for?

The plug is designed for circular holes with a nominal diameter of 21 mm on metal, plastic, ceramic, concrete or panel sheets. As long as the material thickness is within the allowable range, the plug will fit tightly without the need for adhesive.

Can it be used outdoors for a long time?

For the Standard and Good types, the product withstands short-term sun and rain very well. If it needs to be used outdoors for a long time under strong sunlight, you should prioritize the High-grade or Heat-resistant series to improve durability and limit rubber aging.

Can you manufacture custom colors and sizes?

Yes. We can manufacture to order: change dimensions, profile, hardness and color (black, white, gray, blue, red…). You just need to provide drawings or physical samples, and our technical team will advise and give a detailed quotation.

Do you provide custom manufacturing of rubber plugs?

Yes. For special projects, we support mold design and manufacture of rubber plugs to custom sizes, from small trial quantities to mass production.
➤ See more details here

Where can I learn more about rubber types used for plugs?

Depending on the working environment, you can use NR, CR, EPDM, silicone… Each type has its own advantages in elasticity, chemical resistance and temperature range.
➤ Learn more about rubber types here

How to select the most suitable Ø21H10 rubber plug for my application?

Clearly determine the hole diameter, material thickness, working environment (indoor, outdoor, with or without oil), and aesthetic requirements, then choose the rubber type and quality grade accordingly.
➤ See detailed selection guidelines here