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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
London Gather 9 x 6 inch - Ø 125

London Gather 9 x 6 inch - Ø 125

61-125-LG6
£80.99 (including VAT)
In stock
London Gather 9 x 9 inch - Ø 125

London Gather 9 x 9 inch - Ø 125

61-125-LG9
£89.99 (including VAT)
In stock
Mi-Flexwrap 10m x 12mm Insulated Blanket  125mm or 150mm

Mi-Flexwrap 10m x 12mm Insulated Blanket 125mm or 150mm

90-FW600-10
£235.99 (including VAT)
In stock
Mi-Flexwrap 10m Kit (10m Blanket, 20 Bands, 12m Tape) 125mm or 150mm

Mi-Flexwrap 10m Kit (10m Blanket, 20 Bands, 12m Tape) 125mm or 150mm

90-FW600-10K
£274.99 (including VAT)
In stock
Leca 50L Bag

Leca 50L Bag

90-LECA
£27.99 (including VAT)
In stock
Rockwool Tube - 1000mm long  125mm

Rockwool Tube - 1000mm long 125mm

90-RPS-125
£34.99 (including VAT)
In stock
Aluminium Tape

Aluminium Tape

90-RPS-T
£26.99 (including VAT)
In stock
Vermiculite (100L Bag)

Vermiculite (100L Bag)

90-VERM
£34.99 (including VAT)
In stock
Debris Collar with Jubilee Connector - Ø 125

Debris Collar with Jubilee Connector - Ø 125

94-COLLAR-J-125
£14.99 (including VAT)
In stock
Register Plate (F) - 900x495, no access hole - Ø 125 & 150

Register Plate (F) - 900x495, no access hole - Ø 125 & 150

94-REG-F
£30.99 (including VAT)
In stock
Register Plate (G) - 900x495, 2 access hole - Ø 125 & 150

Register Plate (G) - 900x495, 2 access hole - Ø 125 & 150

94-REG-G
£56.99 (including VAT)
In stock
Register Plate (H) - 900x600, no access holes

Register Plate (H) - 900x600, no access holes

94-REG-H
£51.99 (including VAT)
In stock
Pot Hanging Cowl 1mm (Natural) - Ø 125

Pot Hanging Cowl 1mm (Natural) - Ø 125

20-125-PHCM1
£67.99 (including VAT)
Out of stock
PH Cowl - Ø 125

PH Cowl - Ø 125

20-125-PHCMB
£66.99 (including VAT)
Out of stock
PH Cowl - Buff / Straps / Mesh x 125mm - Ø 125

PH Cowl - Buff / Straps / Mesh x 125mm - Ø 125

20-125-PHCMC
£94.99 (including VAT)
Out of stock
Pot Hanging Cowl 1mm (Painted) - Ø 125

Pot Hanging Cowl 1mm (Painted) - Ø 125

20-125-PHCMT1
£73.99 (including VAT)
Out of stock
MI-FLEX Pot Hanging Cowl (Terracotta) Ø 400 Lid - Ø 125

MI-FLEX Pot Hanging Cowl (Terracotta) Ø 400 Lid - Ø 125

20-125-PHCMT400
£69.99 (including VAT)
Out of stock
MI-FLEX Square Pot Hanging Cowl (Natural) - Ø 125

MI-FLEX Square Pot Hanging Cowl (Natural) - Ø 125

20-125-SPHCM
£71.99 (including VAT)
Out of stock
MI-FLEX Square Pot Hanging Cowl (Terracotta) - Ø 125

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

20-125-SPHCMT
£75.99 (including VAT)
Out of stock
MI-FLEX Pot Hanger Support Clamp - Ø 125

MI-FLEX Pot Hanger Support Clamp - Ø 125

20-125-SUPCL
£10.99 (including VAT)
Out of 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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