Every Akermin recommendation is built from documentation, not from marketing copy and not from invented testing. This page explains exactly what we check and what a product must show to earn a spot in a guide.
The evidence we use
- Manufacturer documentation. Datasheets, user manuals, published accuracy and range specifications, calibration procedures, certification listings and warranty terms.
- Sensor technology fundamentals. How a measurement principle behaves (for example NDIR versus metal-oxide CO₂ sensing) tells us what a product can and cannot do regardless of the brand.
- Standards and public guidance. Ventilation benchmarks, safety categories such as multimeter CAT ratings, and published exposure guidance from public bodies.
- Owner feedback patterns. We read verified-purchase reviews for recurring problems (drift, connectivity, battery life, app failures), not for star ratings.
- Amazon product data. Used only for images, availability and links. It is never the authority for a technical specification.
What a product must show
- A stated measurement method and range that fit the job the guide is about.
- A published accuracy or tolerance figure. Products that do not publish one are called out as such.
- A documented calibration process the owner can actually perform.
- Power, connectivity and logging that match how the product will realistically be used.
- No recurring, unresolved failure pattern in owner feedback.
What we do not claim
We do not run a laboratory and we do not publish figures as if we had measured them. When a page says “verified specifications”, it means we verified the manufacturer’s published specification against the current documentation, not that we measured it ourselves.
Ranking and badges
“Best Overall” goes to the product whose documented characteristics best fit the widest range of buyers in that guide. “Best Value” is the lowest-cost product that still meets every requirement above. Category badges such as “Best for Smart Homes” describe a fit, not a superiority ranking.
Updates
Guides are re-checked when a manufacturer revises a product, when owner feedback changes materially, or at least once a year. The update date appears at the top of every article.