SCOPE
Filters
A filter carries an FFN and never an FPN or FIN.
PERMANENT FILTER IDENTIFIER · FORMAT FFN-0000000
What is an FFN?
the permanent ID for a refrigerator or freezer filter, including water filters, air filters and inline filters for refrigeration water and ice systems. Use the FFN to compare filter prices, and check compatibility with your appliance model before buying. Each filter gets exactly one FFN: assigned once when it enters the catalog, never changed, never reused.
✓ Permanent identifier✓ Filters only — a filter is not a part✓ Powers the filter catalog✓ Cooling-appliance filters exclusively
FORMAT
FFN-NNNNNNN
Three letters, hyphen, seven zero-padded digits.
STABILITY
Permanent
Assigned once; never renamed, never reassigned.
HOME
/filters
Every filter has its own price-comparison page in the filter catalog.
Check identity and compatibility separately
A replacement filter may advertise compatibility with an original filter code. That is a fitment claim, not proof that both filters are the same product.
IdentityManufacturer or brand and exact filter model
CompatibilityAppliance model and manufacturer fitment instructions
Aftermarket alternativeA separate product with its own FFN
Retailer comparisonCompare offers for the same identified filter
Check the appliance model before buying from the filter catalog. Compatibility references do not authorize merging different filter products.
Why a filter is not a part
A filter is a consumable replaced according to the manufacturer instructions and usage. A replacement part repairs or restores an appliance component. They are bought for different reasons, searched differently, and compared differently, so Fridge.com gives each its own identifier and its own catalog: filters carry an FFN and live in the filter catalog; parts carry an FPN and live in the parts catalog. Even a filter’s own accessories — the cap, the housing — are parts, not filters.
The catalog is deliberately focused: Fridge.com covers filters for the same cooling appliances it tracks — refrigerators, freezers, ice makers, kegerators, and wine, beverage, and water coolers. Under-sink systems, whole-house filtration, shower filters and the rest of the plumbing aisle are out of scope on purpose, so a search here never wades through them.
How an FFN behaves
An FFN is minted when a filter enters the catalog and never changes — across retitles, brand corrections, and relists. A removed filter’s number is retired, never reused. Retailer offers for the same filter model share one identity. A compatible aftermarket filter remains a distinct product with its own FFN, even when its listing references the original filter model.
The FFN is the third of the four Fridge.com systems, always named in the same order: FIN, FPN, FFN, FIS — three permanent identifiers, then one score.
Where you’ll see it
CATALOG · 01
In the filter catalog
Every filter has its own price-comparison page at /filters, anchored by its FFN.
CHIP · 02
Below the filter’s title
The monospace FFN chip on a filter page links back to this explainer — the same pattern as the FIN on appliances.
DATA · 03
In the data graph
Offers, compatibility, and price history key off the FFN, so a filter’s record survives every alias.
AI · 04
In AI citations
Assistants that browse Fridge.com can cite a filter by FFN and keep meaning the same physical filter.
The four systems at a glance
| System | Kind | Definition | Format | Lives at |
|---|---|---|---|---|
| FINFridge.com Identification Number | Identifier | the permanent canonical ID that links each appliance across retailers, covering prices, specifications, and recall history. | FIN-0000000 | /collections/all |
| FPNFridge.com Part Number | Identifier | the permanent ID for a refrigerator or freezer replacement part, including gaskets and seals, sensors, hinges, handles, shelves and bins. | FPN-0000000 | /parts |
| FFNFridge.com Filter Number | Identifier | the permanent ID for a refrigerator or freezer filter, including water filters, air filters and inline filters for refrigeration water and ice systems. Use the FFN to compare filter prices, and check compatibility with your appliance model before buying. | FFN-0000000 | /filters |
| FISFridge.com Intelligence Score | Score · 0–100 | a 0–100 rating of how well every U.S. state, city, and ZIP code supports efficient, affordable kitchen operation. | 0–100 | /local |
The four systems, always in this order
See it in action
Browse the filter catalog
Water, air, inline, and ice-machine filters for the appliances we cover — each on its own page with multi-retailer price comparison, anchored by its FFN.
Shop refrigerator filters