Standard 1-inch slot
A thin, framed filter slides into a narrow rack or return grille.
Next: Read all three size numbers on the filter. Confirm the actual dimensions and airflow direction.
Understand 1-inch filtersNot sure where to start?
Look at the opening and the label
These simple diagrams are orientation guides. Match the label and dimensions before ordering.
Standard deep filter opening
A deeper framed filter slides into a rack, often marked 4 inches.
Next: Check actual depth: products with the same nominal size can differ. A deep opening alone does not establish a fit.
Check deeper filter fitAprilAire media cabinet
A labeled cabinet holds replacement media designed for that cabinet.
Next: Find the cabinet model on its label. For a 1410, start with the 1410 guide; do not select by 16x25 alone.
See the 1410 exampleRails or expandable media
The media expands onto rails, or an existing cabinet uses a conversion kit.
Next: Record both the cabinet and kit numbers. Upgrade media and standard replacement media are separate purchase paths.
Understand rails and kitsA thin filter inside a deep cabinet?
Do not assume the thin filter is the intended replacement. Check the cabinet’s specified media and rail arrangement. Gaps around a filter can let air bypass it.
What to record before asking for help
Note the filter size, actual dimensions, cabinet label, media number and any kit number. For your own reference, take one photo from farther back showing the furnace or air handler, then a closer photo showing the full cabinet/rack and its connection. Keep private details out of anything you share.
If the filter path or airflow is uncertain, ask a qualified HVAC professional before changing the setup.