A very well made quality product, easy to fit and significantly more powerful than the little centrifugal fan it replaced. Little noise escapes ‘sideways’ from the system, and the fan is 2 metres from in the bathroom itself, but sound from the inlet pipe even on the slow setting, was startling. Lining the inlet tube with carpet did remove the ‘hiss’ and adding a baffle box did considerably quieten the hollow roar. So a very effective fan, but I wish I had understood what a decibel rating of 20 really meant.