Reddit reviews Can Steel Flange, 6-Inch
We found 1 Reddit comments about Can Steel Flange, 6-Inch. Here are the top ones, ranked by their Reddit score.
Steel flange for filters and ductingIncludes foam gasket tape to hold flange in placeIncludes 6 tek screws to secure flange to filter
Make sure the carbon filter has a flange.
It looks like this
 
Otherwise, you might need a connector (Ducts have a male/female)
See this as an example
 
I bet it's the flange though