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125MM (5 INCH) Flue Liners & Install Kits - MI-Flex, 904L Mi-FLEX

Discover top-tier 125mm (5 inch) flue products including MI-Flex and 904L Mi-FLEX solutions for your fireplace. Ensure a secure and efficient installation with our superior flue liners, fixings, terminals, insulation, and more.
Discover top-tier 125mm (5 inch) flue products including MI-Flex and 904L Mi-FLEX solutions for your fireplace. Ensure a secure and efficient installation with our superior flue liners, fixings, terminals, insulation, and more.


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The best selling flue liner in the UK. Suitable for gas, oil, and approved solid fuels. Call our advisers on 01670 206 999 if you need any help choosing.

£1.93 £1,844.99
Showing 20 of 82 items
Top Hat Adaptor - Ø 125

Top Hat Adaptor - Ø 125

20-125-THA
£58.99 (including VAT)
In stock
Register Plate Adaptor - Ø 150

Register Plate Adaptor - Ø 150

20-125-THAR
£88.99 (including VAT)
In stock
Chimney Notice Plate

Chimney Notice Plate

20-CNP
£1.93 (including VAT)
In stock
Chimney Notice Plate - 50 Pack

Chimney Notice Plate - 50 Pack

20-CNP48
£90.99 (including VAT)
In stock
MI-FLEX FastFix-Screw Adaptor to SW - Ø125

MI-FLEX FastFix-Screw Adaptor to SW - Ø125

21-125-MAE
£14.99 (including VAT)
In stock
MI-FLEX FastFix-Screw Hanging Cowl (Terracotta) - Ø125

MI-FLEX FastFix-Screw Hanging Cowl (Terracotta) - Ø125

21-125-PHCMT
£55.99 (including VAT)
In stock
Screw-FIX Joiner - Ø 125

Screw-FIX Joiner - Ø 125

25-125-J
£41.99 (including VAT)
In stock
Screw-FIX Adaptor to SW - Ø 125

Screw-FIX Adaptor to SW - Ø 125

25-125-MAE
£15.99 (including VAT)
In stock
Screw-FIX Adaptor to SW, 1mm - Ø 125

Screw-FIX Adaptor to SW, 1mm - Ø 125

25-125-MAE1
£32.99 (including VAT)
In stock
Screw-FIX Long Tail Adaptor - Ø 125

Screw-FIX Long Tail Adaptor - Ø 125

25-125-MAELT
£28.99 (including VAT)
In stock
Screw-FIX Increaser - Ø 125-150mm

Screw-FIX Increaser - Ø 125-150mm

25-125-MR
£25.99 (including VAT)
In stock
Screw-FIX Long Tail Increaser - Ø 125-150mm

Screw-FIX Long Tail Increaser - Ø 125-150mm

25-125-MRLT
£43.99 (including VAT)
In stock
Screw-FIX Nose Cone - Ø 125

Screw-FIX Nose Cone - Ø 125

25-125-NC
£16.99 (including VAT)
In stock
MI-FLEX Pot Hanging Cowl (Terracotta) - Ø 125

MI-FLEX Pot Hanging Cowl (Terracotta) - Ø 125

25-125-PHCMT2
£57.99 (including VAT)
In stock
Screw-FIX Pot Hanger - Ø 125

Screw-FIX Pot Hanger - Ø 125

25-125-PHS
£25.99 (including VAT)
In stock
Screw-FIX Rain Cap - Ø 125

Screw-FIX Rain Cap - Ø 125

25-125-RC
£26.99 (including VAT)
In stock
Screw-FIX Register Plate Adaptor - Ø 125

Screw-FIX Register Plate Adaptor - Ø 125

25-125-RPA
£42.29 (including VAT)
In stock
Screw-FIX Register Plate Increaser - Ø 125-150mm

Screw-FIX Register Plate Increaser - Ø 125-150mm

25-125-RPAI
£57.99 (including VAT)
In stock
London Gather 9 x 12 inch - Ø 125

London Gather 9 x 12 inch - Ø 125

61-125-LG12
£92.99 (including VAT)
In stock
London Gather 9 x 19 inch - Ø 125

London Gather 9 x 19 inch - Ø 125

61-125-LG19
£107.99 (including VAT)
In stock
Your 125MM (5 INCH) Questions Answered

What is the difference between MI-Flex and 904L Mi-FLEX? -

MI-Flex is known for its flexibility and ease of installation, while 904L Mi-FLEX offers enhanced corrosion resistance and durability for long-term use in fireplace flues.

Do I need any special tools to install 125mm (5 inch) flue liners? +

Can I use 125mm flue liners for a wood-burning stove? +

How often should I clean my 125mm flue liner? +

Are there any safety precautions I should take when installing 125mm flue liners? +

In the realm of fireplace flues, the 125mm (5 inch) category stands out with its versatile options. MI-Flex and 904L Mi-FLEX products offer durability and reliability in flue liner installations. Whether you need a coil or cut length, our 125mm solutions provide top-notch quality and performance. Pair these with our installation kits, fixings, and insulation for a complete fireplace flue setup. With our range of products, you can trust in a seamless installation that enhances both safety and efficiency for your fireplace.
Why Buy 125MM (5 INCH) Products
The 125mm (5 inch) flue products cater to a range of fireplace setups, from standard residential fireplaces to more customized designs. Whether you're a homeowner or a professional installer, these flue liners and accessories offer the flexibility and quality needed for various installation requirements. Use them to ensure proper venting, maintain optimal airflow, and increase the overall efficiency of your fireplace. Trust in the durability of MI-Flex and 904L Mi-FLEX products to deliver long-lasting performance in your fireplace flue system.

Trusted By Trade Professionals

Our 125MM (5 INCH) products and services are trusted by hundreds of professionals nationwide. We're committed to providing quality and reliability that meets the high standards of our customers.

Dedicated Support

Experience our unparalleled customer service and support when you buy 125MM (5 INCH) from National Flues. Our team is here to assist you every step of the way, ensuring your needs are met with expertise and care.

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