Semi Rigid Flex (3m Long) – 200mm Diameter

It depends on the job. Aluminium foil flex suits general ventilation and fan connections, with an insulated version for warm, moist air runs. Combi flex is a tougher aluminium/polyester construction. PVC grey flex suits light commercial extract, PU anti-static flex is made for dust and chip extraction, semi-rigid flex holds its shape once formed, and double-ply silicone flex handles high-temperature air. Ring us if you’re unsure which suits your application.

Lengths vary by type: aluminium foil flex (insulated and uninsulated) comes in 10m lengths, combi flex in 6m, double-ply high-temp silicone flex in 4m and semi-rigid flex in 3m. Flexible ducting compresses for transport and is easily cut to the length you need on site, so one supplied length will often do several short connections between fans, spigots and grilles.

Most ranges run from 80mm to 500mm to match standard spiral duct and fan spigot sizes, including 100mm, 125mm, 150mm, 160mm, 200mm, 250mm and 315mm. Semi-rigid flex covers 100mm to 355mm, PU anti-static flex 80mm to 315mm, and the high-temp silicone flex starts at 38mm for small hot-air and fume lines and runs up to 300mm.

Slide the flex over the spigot or male connector by at least 50mm, then secure it with a hose clip and seal with foil duct tape for an airtight joint. We stock quick-release hose clips in four sizes covering ducting up to 525mm diameter, plus foil tape in 50mm and 100mm widths. Keep runs as short and straight as possible to maintain airflow.

Use insulated aluminium flex where warm, moist air passes through cold spaces — bathroom or kitchen extract through a loft, for example — because the insulation reduces condensation forming inside the duct and dripping back. Uninsulated foil flex is fine for short connections in heated spaces, supply air at room temperature, or anywhere condensation isn’t a concern. Both come in 10m lengths across the same 80mm to 500mm sizes.

Yes — all our flexible ducting ranges and hose clips are stock items with next-day availability shown on the product pages. Delivery is free on orders over £400 excluding VAT. If you’re ordering flex alongside a fan, matching the flex diameter to the fan spigot size makes installation simpler, and our team can confirm compatibility before you order.