bought and never used, cost £15

PATIKIL 10 to 8 Duct Reducer Connector, Heating Cooling Ventilation Tube Fire-Resistant Increaser Adapter Pipe Fitting for Vent System, Grey

• Inner Diameter: 250 x 200 mm / 9.84 x 7.87 inch (Big*Small); Size: 92 x 4 mm / 3.62 x 0.16 inch (H*T)
• Advantage: 1. Make of durable PP material, lightweight, waterproof, moisture resistant and wear-resistant, fire-resistant and pressure resistance, not easy to deform, can be used for a long time; 2. The reducer design can make the ventilation more smooth within two different size of the pipes, allowing you to lengthen and extend your ducting and meeting your various DIY pipe decoration needs.
• Instruction: Easy to install, just connect the two ends of the connector with pipes of appropriate size.
• Application: This duct pipe reducer connector is used to connect the pipes of equipment such as bathroom fans, range hoods and dust collectors to the ventilation duct system, you can connect two air ducts of different diameters to create a seamless ventilation system duct. Suitable in home, offices, kitchen, factory or apartments.
• Note: Please choose the right size according to your needs and note that they can be used in the temperature range of - 10 ℃ to 70 ℃.