Product review (5 stars): Work excellently
There is another view stating that this filter is flimsy and keeps blowing open. I have no idea what they mean. This filter has a mesh wire backing that allows the user to bend it into place in the proper vent cover and it most definitely holds its shape. You can even fold down one side and tuck it under the lip of the vent cover. Yes, you will have to fill it often, especially if you have a very dry house/have your heat on high and often/live in a dry climate. But it certainly does the job at quietly keeping your house humidified. The only way they could improve this product is by making it come pre-treated to resist absorbing minerals and becoming stiff. Once it does this, it is not effective anymore. You can add a dropped of humidifier treatment liquid to the water you pour in these and that helps a lot, but it just adds another step.