Holly Brennan, Heaters & materials editor

I'm the one who reads the warranty small print. With saunas it matters more than people expect: the heaters and the cabin are often covered for different lengths of time, and the conditions sit in a PDF most buyers never open.

Heaters are my other subject. Listings mix up far infrared, near infrared and full spectrum, and the panel count tells you less than the wattage and where the panels actually sit. Low EMF is the claim I'm most careful with. When a seller prints a figure, I look for how it was measured and at what distance, and if the paperwork doesn't say, our guide says that too.

I also write the cleaning and maintenance guides, which mostly means reading the care instructions for each wood and finish and comparing them with what owners report a year later. Accessories get the same treatment. I'd rather you buy two things you'll use than a bundle of ten.

None of this involves sitting in a cabin with a meter. It's careful reading, side-by-side tables and a great many owner reviews.