Not bad, but unfortunately reduces the flap 150-channel at 120 !!!

Itself is very well-made product, which was unfortunately realized only 70% of Original Idea! At the end of the channel, the valve reduces a 150 Ø exhaust duct Ø 120 and that's a fat downside!
One builds a 150 ° channel, so that it lets through enough air and hood runs quietly, but in the end the one castrated using this flap 120, somehow illogical, right? !!!

When the flap as an insertion flap for 150-channel is established, you could produce the much more precisely and thus avoid external seal need! As an example, Messrs. Marley manufactures flap absolutely 100% accurate with no external seals in 150er channel fit in !!!
Second seal is interior seal which almost 10 mm high, superfluous unnötigerem drag !!!