"extractor fan busted so purchased a new one never checked the flue size,when it arrived the flue kit was 120 mm hole in wall to big,screwfix to the rescue 150mm to 120 mm reducer £1.34 fitted upside down JOB DONE"
"This was used as part of two pieces to reduce an extractor from 150 to 100, so I could attach an extractor to an external vent. The kit provided with the (non-screwfix) fan only reduced to 125 !! It was german !!"
"I had to use one of them with my new cooker hood extractor to reduce the diameter as it came up with 150 mm open end extract hole. Looked elsewhere but cheapest found at Screwfix. check the stock online & popped in picked it up, job done."