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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
904L Mi-FLEX 125mm x 1m CUT LENGTH

904L Mi-FLEX 125mm x 1m CUT LENGTH

36Z-125-1
£31.99 (including VAT)
In stock
904L Mi-FLEX 125mm x 44m COIL

904L Mi-FLEX 125mm x 44m COIL

36Z-125-44
from £1,844.99 (including VAT)
In stock
Jubilee Clip and Banding Ø 200 - 800mm length

Jubilee Clip and Banding Ø 200 - 800mm length

13-JUBILEE-200
£3.99 (including VAT)
In stock
Jubilee Clip and Banding Ø 300 - 1000mm length

Jubilee Clip and Banding Ø 300 - 1000mm length

13-JUBILEE-300
£4.99 (including VAT)
In stock
Increasing MI-FLEX Adaptor - Ø 100-Ø 125

Increasing MI-FLEX Adaptor - Ø 100-Ø 125

20-100-MR
£20.99 (including VAT)
In stock
Top Clamp - Ø 125

Top Clamp - Ø 125

20-125-C
£9.99 (including VAT)
In stock
Gather Hood (300x300) - Ø 125

Gather Hood (300x300) - Ø 125

20-125-GHM
£127.99 (including VAT)
In stock
Gather Hood Small (300x200) - Ø 125

Gather Hood Small (300x200) - Ø 125

20-125-GHS
£118.99 (including VAT)
In stock
Joiner - Ø 125

Joiner - Ø 125

20-125-J
£21.99 (including VAT)
In stock
MI-FLEX Adaptor - Ø 125

MI-FLEX Adaptor - Ø 125

20-125-MAE
£19.99 (including VAT)
In stock
MI-FLEX Adaptor 1mm - Ø 125

MI-FLEX Adaptor 1mm - Ø 125

20-125-MAE1
£30.99 (including VAT)
In stock
Long Tail MI-FLEX Adaptor - Ø 125

Long Tail MI-FLEX Adaptor - Ø 125

20-125-MAELT
£24.99 (including VAT)
In stock
Mini Pot Hanging Cowl 1mm (Natural) - Ø 125

Mini Pot Hanging Cowl 1mm (Natural) - Ø 125

20-125-MINIPH1
£124.99 (including VAT)
In stock
Mini Pot Hanging Cowl 1mm (Painted) - Ø 125

Mini Pot Hanging Cowl 1mm (Painted) - Ø 125

20-125-MINIPHT1
£132.99 (including VAT)
In stock
Increasing MI-FLEX Adaptor - Ø 125-Ø 150

Increasing MI-FLEX Adaptor - Ø 125-Ø 150

20-125-MR
£22.99 (including VAT)
In stock
Increasing MI-FLEX Adaptor 1mm  - Ø 125-Ø 150

Increasing MI-FLEX Adaptor 1mm - Ø 125-Ø 150

20-125-MR1
£43.99 (including VAT)
In stock
Increasing MI-FLEX Adaptor - Ø 125-Ø 175

Increasing MI-FLEX Adaptor - Ø 125-Ø 175

20-125-MRD
£68.99 (including VAT)
In stock
Long Tail Increasing MI-FLEX Adaptor - Ø 125-Ø 150

Long Tail Increasing MI-FLEX Adaptor - Ø 125-Ø 150

20-125-MRLT
£38.99 (including VAT)
In stock
Nose Cone - Ø 125

Nose Cone - Ø 125

20-125-NC
£5.99 (including VAT)
In stock
Top Plate - Ø 125

Top Plate - Ø 125

20-125-P
£11.99 (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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