Connector with Backflow Flap, Check Valve, Connector, Ventilation Pipe, Round Duct, Ventilation System, Pipe Connector, Diameter 100 mm, White

Fit a 4" bath vent with no issues

No gaskets or o-rings to help seal, but should stop most back draft. Here is a much better one: AC Infinity 4" Backdraft Damper, One-Way Airflow Ducting Insert with Spring-Loaded Folding Blades for 4” Ducting in Range Hoods and Bathrooms Fans https://a.co/d/hodpLQl I used this one in a corner just above the room and the better one at the outside wall. Fits nicely into a 4" 90.

Nice damper for 4 inch metal ducting, used it to isolate the existing dryer exhaust duct, from an ad hoc fan driven exhaust to vent my cat’s sealed litter box cabinet. Must install vertically. The existing dryer flow creates outward suction which seals the damper so there is no backdraft towards the newly installed fan exhaust ( very necessary to minimize lint to build up). When the fan is in operation ( with or without the counter dryer suction) the damper opens up and allows the stink to vacate my basement.. just what I needed...( the damper is installed between the t-shaped duct and the flexible piping in the picture)

works great

I have been searching for some kind of 'automatic one way' check valve to install on a 4" air ventilation line. It needs to open with the relatively low air pressure provided by inline duct fans and shut completely when the fan is off. In my case this just did not work. It will open under the pressure of an inline fan but even when the fan is off it opens under the natural draft as colder air wants to move in through the fan as well. That might work for some applications but not what I needed. The flapper does seem to swing open and shut whether mounted horizontally or vertically. While I did not expect the flapper to be of heavy material I was surprised by how thin and light the body of the unit was. The housing on the flapper valve does appear to be pretty flimsy.

It worked, it fit, and should work good long term for my purposes.

Lightweight. It was easy to install and works as supposed to

This part has not spring and can be opened by pushing on either side of it, in other words if the wind blows into the ventilation fan the damper does not stop it, air will flow both directions so what is the point?

Wanting to replace two rubbish "Silavent" ceiling extractor fans with inline fans, I needed to source to vents with shutters, but none were available. So I bought two KAIR vents and two of these. They fit standard 4" (100mm) solid or flexible duct pipe. These are unsprung gravity flaps, so they need to be fitted nothing but vertically to operate properly. Fitted any other way and they won't close. They are also best fitted at the vent in the ceiling so they become dual purpose backdraught and odour eliminators. They seem good quality and due to them not having springs, there's nothing to go rusty and stop working.

Gut und preiswert.

terugslag die goed werkt en eenvoudig aan te brengen is

bon rapport qualité-prix

Very flimsy and doesn’t work with 100mm pipes (too small, which makes me think it would be even worse with 4 inch pipes).