Primary sources first. Specs come from manufacturer manuals, data sheets and brochures; sizing values from utilities and government agencies. Retail listings are cited only to point out where they disagree with the manufacturer.
Every number is sourced. Each figure links to a numbered source with the document date and the date we accessed it.
Test conditions are shown. When brands measure differently (for example, pump flow on battery vs. on a bench power supply), we show the condition next to the number instead of ranking them as if they were equal.
Calculators show their formula. Each tool explains its math on the page and says what it ignores.
Research is assisted by software. We use automated tools, including AI, to find and extract data from documents. A person checks extracted numbers against the source before publishing.
Corrections. If you find an error, tell us and we'll fix it and note the change.