Round Connector 100mm - 4 inch to Connect Duct Pipe or Flexible Ducting Hose

Taped this to the back of my bathroom fan. I had to remove the raised centre via filing it off to fit into a 110mm pipe. Works perfectly.

I installed this in a vertical duct above my cooker hood. I was getting cold draughts coming in during the winter and this completely solved that problem.There was one small issue in that when mounted vertically it is possible for the flap to open more than 90 deg, tip past the vertical and then stick in the open position. I added a small screw to prevent it opening more than about 85 deg and this seemed to fix that issue.

Bought this to retro fit in the ducting of a 12v Manrose bathroom fan which, for some reason and unlike its predecessor, came without a backdraft shutter.As other buyers have mentioned, its a tight fit in 100mm ducting and I had to trim the outer central ridge on the shutter to fit it inside the ducting. Used a very sharp paperhangers knife to shave a millimetre or so from the ridge and it now fits perfectly, held in place, just in case, by a blob or two of silicone. Its working well so far: yes, it clatters when the wind blows but that goes with the territory when, as we do, you live in a windy coastal town. Not sure how long it'll last given the wear that the wind will place on the shutter's basic hinges, but Time will tell.Very easy to retro fit if you have the access, so recommended.

125mm round plastic duct connector from Kair. Good durable product and a snug taper push-fit into the standard 125mm (internal diameter) plastic solid duct.The slight taper on the connector ends grips the duct securely meaning that additional duct tape might not be required.But in an inaccessible invisible place where leaking condensation drips might cause damage I usually add a wrap of tape anyway, just in case age and de-plasticizing or vibration might slacken the grip.This is ideal for use inside a building and protected from the UV of bright sunshine.

Very expensive doe what it was and small fit wasn’t great then out already as was flapping at night and vey loud tapping

The media could not be loaded. If you use this at time of install then the external raised ridge helps you fit one pipe up to the other, with this 'connector' with the backdraught stopper in it. HOWEVER, If you are retro fitting this inside an existing piece of pipe/ducting then the ridge will not allow it to slide snugly inside. NO WORRIES just get your stanley knife to carve it off as I have done with mine and sand it smooth if you like, like I have. TO STOP THE CLATTERING TAPPING BANGING NOISE of plastic-against-plastic, as the wind slams it open-and-shut get yourself a piece of felt or such-like firm-ish non organic fabric (so it dunt rot or get bacteria and mould in it) and draw a chalk mark around for the semi-circle using this connector as a template, where you will cut inside the mark you've made. Then, using double-sided tape, cover your semi-circle fabric in this tape (I used carpet tape, wide and strong. Then cut the excess tape off and make sure the size fits the flap right to the edge. This is so that when the flap hits the ridge to stop the wind/backdraft/cold howling gales coming into your house it won't make a godforsaken noise that drives you more insane than the cold. I've done this today and it took less than 10mins once I'd gathered all the materials. THE FLAP NEEDS TO BE FLIMSY/RUBBISH (quoting others on here) because it has to be able to move easily to let your extracted steam out with your fan, if it wasn't flimsy it wouldn't work, so be gentle with it. Anyway, I'm happy, hope you're happy too-oo-oo

I had to make some minor adjustments: Sand down the collar until it snugly fit inside the 100mm dia tube. Put graphite powder on the swivel pins and stick a small weight to the bottom of the flap so that it closed sufficiently to stop most of the backflow. The backflow seems to have now significantly reduced... time will tell.

Bought this to replace an old one I had that had a spring in it and 2 flaps. The design of the new one seems a lot better as there's less moving parts. It fitted easy enough but I will see how it gets on. In our vents there's eventually a build up of various fluff/dust in the pipes. It's useful to clean these out every few years and this is how I found the previous shutter wasn't working too well and needed replacement.Just need to make sure this new part is fitted the correct way up otherwise it isn't going to work - pretty obviously really though.