For Ep T673 Dye Ink Compatible EcoTank Inkjet Printer Epson L1800, L805, L800, L810, L850 Printer (4*70 ml) Black Ink Bottle

The maker's exact model code. Printer families share marketing names across very different machines, and the cartridge that fits depends on this code, not the family name.

Whether the machine prints in colour or black only. A monochrome laser is markedly cheaper to buy and to run when colour is never needed.

What kind of consumable this is. Drum units and maintenance kits are periodic replacements separate from ink or toner, and their cost is easy to overlook when comparing running costs.

The exact supply codes this machine takes. It is the single most useful fact in the category and almost never on the product listing: supply availability and cost decide the real cost of owning the printer.

How many pages one cartridge or bottle set prints, to the ISO standard at 5% coverage. Real documents with images use far more, so treat it as a comparison figure between models rather than a promise.

Whether each colour is its own cartridge. With a combined tri-colour unit, running out of one colour means replacing all three.

Whether the machine accepts refills or third-party supplies without a chip check. Chipped models can refuse cheaper alternatives or after-market refills entirely.

Width x depth x height in millimetres. Check the depth with the trays extended, which is often much more than the closed figure.

A link to the maker's own specification page for this exact model. It is the source a disputed fact here should be checked against, and it is where the supply codes are confirmed.

Which revision of the maker's spec page these facts were read from, as a date or version. Makers quietly edit spec pages after launch, so this records which wording was in front of us.