I was quite disappointed with how much smaller than my 3M filters these were. I can't complain much because the real sizes were clearly stated when I purchased them. I just did not realize that it is NOT standard behavior in the industry to make the filters significantly smaller than rated size, and it created significant problems in my firnace to make them properly seal and do a good filtering job. Next time, I will need to order a 5" filter to fit properly in my unit which was constructed to safely fit a real 4" filter that was a full 16" wide.
It seems weird to me that Trane would use a hard to find size filter in one of their top of the line HVAC units, but FilterBuy is the only place I was able to find a high quality replacement that fits.
These were not a replacement for the Honeywell filters I had that indicated the same size on the box. Probably my fault for not reading further on the fine print - i assumed a filter size was a filter size.