200mm

Brewer UFO Anti Downdraught Chimney Liner Cowl - will fits Chimney Pots with an external diameter of up to 300mm. If you have a problem with downdraught and are burning solid fuel (wood, coal or oil) or using a gas system then the UFO (Ultimate Flue Outlet) Flue Liner Cowl is a great solution and has been used for many years to great effect. The UFO"s specially shaped discs channel wind to create an updraught (or lower pressure) at the top of the system to counteract wind related downdraught.