How we verify

FitmentList exists because the fitment-answer layer of the filter market is sloppy: wrong OEM matches, empty certification fields, and prices quoted without a source or a date. The rules below are the whole product.

Fitment

Manufacturer data first. When a manufacturer publishes a filter finder or a fit list, it arbitrates. Retailer fit lists (PartSelect, RepairClinic, FiltersFast, DiscountFilters and others) are harvested whole, and conflicts between sources are resolved conservatively — a model in dispute is excluded rather than guessed, and the conflict is written into the research notes. A model is never added from a single marketplace listing.

Certification

For fridge filters, "certified" is printed only when the cartridge appears in the certifier's own directory (NSF, IAPMO R&T or WQA) for the standards claimed. Claims that appear only in brand or retailer copy are labeled maker-claimed. Aftermarket cartridges are judged on their own listings — a compatible fit never inherits the OEM cartridge's certification.

Prices

Every price was read from the named store's page on the checked date and is stored with its pack size, shipping terms and source URL. Shipped totals are shown only when the store's shipping terms make the total honest arithmetic. Amazon blocks automated price reads, so Amazon appears as a buy link (with our Associates tag) and never as a quoted price. The lowest verified price headlines each page even when the seller pays us nothing; the Amazon button is never labeled "best price" unless it is.

No page until the record is complete

Models live in the dataset and in fit lists — there are no per-model pages, because a page that adds nothing over the part page helps nobody. A part whose fit is published only at brand level says exactly that, in words, instead of showing an empty list.

Corrections

Fitment data decays: cartridges are renamed, lists are corrected, prices move. Prices are re-verified weekly; if you find a wrong fit, the part page's source list shows exactly where the claim came from.