neverest® RK 4 inch Backdraft Shutter 100mm Ducting Connector Galvanized Steel with Rubber Sealing Fits Only with Metal Ducts

Does the job perfectly. Well made and easy to fit. Quiet - no noise opening and closing. Well engineered. Would definitely say worth the money

Great product have tried numerous different products and this seems to work best for me

Some have commented that the flaps don't close. I've installed these on three fan / ventilation pipes and they all work fine. I install with the hinge vertically, so the flaps open like doors and close easily. I put them on the exit side of the fan, so the maximum force pushes them open, because in strong winds backdraft can push them shut.

Easy to fit on top of the ceiling extractor fan. OK, I had to change the associated fittings a bit, but the job was done and dusted within an hour. Since then (about three weeks ago) there has been no rattling in the wind and the fan is working better than it did before.

This product seems quite well made for the price. It has rubber dampers to stop tapping / rattling noises and closes completely and opens sufficiently wide that the existing ceiling fan is more efficient. I ordered this after measuring the existing fan and checking the technical specifications of the existing ceiling fan. The tubing that the draught excluder is built into is precisely the size of the fan (100mm). Logic would determine that it would be 2-3mm larger at the end that attaches to the fan so it can slide on making a neat and airtight seal. Instead, it sits exactly on top of it. This would be a huge problem on a horizontal fan. I’ve had to tape this in place to make a seal and prevent it moving when the fan is in use or air blowing through the ducting from outside. This is the reason for the lower stars or it would most likely get 4/5. Good product let down my illogical design flaw.

Quality build. Spring perfect resistance. Installed into Cooker Exhuast. Fan 1 and the flap open nearly half, But if fan 2or 3 the flap open full. No draft air coming inside at all.

Installed this in my loft, connecting it to a vent pipe running out from the kitchen hood. Works perfectly and the shutters open even when the fan is on its very slowest speed. Do keep it vertical when installing the unit as this is what it was designed for.

Update! The spring keeping the flaps closed failed due to rust! Now fit for the bin! Dec.'25.This is an inline device and will not fit into your existing fan, you will have to cut your vent tube/pipe in half to be able to install. The seal is not rubber, it is a sponge type material, which is not as absorbent as rubber, so you will get a soft clap sound every time there is a pressure differential. I have a humidity sensor in that bathroom and I'm still seeing a small amount of outside humidity, suggesting that the seal when closed is not great. Disappointed to find that it is not a rubber seal - this is false advertising! If I find another solution, I will be returning this unit.

Muy buen producto, cumple su función a la perfección, sin embargo solo debe utilizarse en horizontal, no apto para usarse verticalmente.

Molto facile da istallare e ottimo funzionamento

Matériel de qualité et étanche avec ressort inox

Diamètre respecté mais ressorts un peu forts

Qualität ist absolut einwandfrei. Öffnet schon auf Stufe 1 meiner Abzugshaube. Ist zwar etwas kleiner als der Rohrinnendurchmesser, dafür passt es aber rein und kann ggf. mit Panzertape ausgeglichen werden. Ich bin damit sehr zufrieden.