A missing lid can look like a simple size problem until several similar rectangles appear in the search results. Build the identity record before choosing a replacement. For a concrete example, IKEA's US page identifies plastic rectangular lid 405.779.43 and links a 34-ounce rectangular glass container, 703.591.99. Both belong to the IKEA 365+ family. The record below matches those named articles through the maker's actual fit statements, rather than treating a familiar brand or equal outer measurements as a universal compatibility rule.
Record the base and lid as separate articles
The base record is: IKEA 365+ food container, rectangular glass, 34 ounces, article 703.591.99. Its US page gives length 8¼ inches, width 6 inches and height 2¼ inches. The replacement record is: IKEA 365+ lid, rectangular plastic, article 405.779.43, listed as 8¼ by 6 inches. Keeping two article numbers avoids mistaking a complete container-and-lid combination for the separately sold part.
Those dimensions are helpful identifiers, but they do not establish the profile of an unknown rim, clip or seal. A box from a different range could share an outer rectangle and still have a different closure. Even within a cupboard of familiar-looking containers, the actual base has to be identified before the published match can be applied to it. No physical container or replacement has been fitted for this article.
Add the maker's relationship, not just two measurements
The lid page says it fits IKEA 365+ rectangular-shaped food containers. The glass-base page says it fits IKEA 365+ rectangular-shaped lids, and the lid listing's linked completion item is this 34-ounce base. Those statements give the two records a documented relationship. The matching 8¼-by 6-inch dimensions accompany that relationship; they are not its only evidence.
A complete private entry could read: 'Base 703.591.99, rectangular glass 34 oz; proposed lid 405.779.43, rectangular plastic; maker pages state reciprocal rectangular 365+family fit; exact base linked from lid listing; no household fit test completed.' This is an original example record. A reader should not copy its base number onto an unidentified older container merely to complete the form.
Keep use permissions attached to the component
The glass base's page lists oven suitability. The plastic lid's page gives its own care instructions, including microwave heating up to 212°F and leaving the lid ajar to release steam. The base's oven statement does not transfer to the lid. A compatibility record answers which component is documented to pair with another, not whether every operation permitted for one is permitted for the assembled pair.
For this reading task, retain the actual lid and base instructions separately and consult them for the intended use. Do not invent an oven setting, a seal-removal method or a leak test from the fact that the articles are related. The manufacturer's first-use washing instruction also belongs with the actual product, rather than being replaced by assumptions based on how clean a new item looks.
Let an unidentified base remain a different outcome
Suppose another household container has no recoverable product reference. Its rim looks similar and a ruler gives an approximately matching length. That second case ends 'base identity unresolved,' not 'same replacement approved.' An appropriate maker enquiry would include the actual available identification and clear views of the relevant part, without forcing a lid onto it to make the question disappear.
For the identified 703.591.99 example, the documentary match is complete enough to identify 405.779.43 as the named replacement candidate. The buyer still needs the real item, its condition and applicable purchasing terms. That is a smaller and more useful decision than replacing an entire cupboard to solve one missing component, while keeping an unknown older base outside the conclusion.
Sources & further reading
Published sources for the details and examples discussed in this story.
