From 180mm

This page groups our 180mm spiral duct reducers — fittings that take a 180mm (approx. 7″) duct down to a smaller diameter, stepping down to 80mm, 100mm, 125mm, 150mm and 160mm. Choose the reducer whose small end matches the next duct size in your system and join it in line with your spiral ducting. These reducers are made to order and despatched in 2-3 working days; orders over £400 ex VAT include free UK mainland delivery.

Other starting sizes are listed under spiral duct reducers.