What to believe on a budget tracker's box
Fitness bands in this price range are widely marketed with claims that the hardware cannot support. 'ECG', 'blood pressure' and 'blood glucose' appear on packaging across this whole category, from many brands, and no wrist device at this price has been through a regulator for any of them.
Two of the products on this page carry ECG wording in the manufacturer's own product name. We list the name as the manufacturer gives it, because that is what is printed on the box you will receive, and we do not repeat the claim as a capability on the product page. Where a supplier has published no specification sheet at all, our page says so.
A wrist sensor produces wellness indicators, not medical measurements. Use the readings to spot a trend and take it to a doctor if something looks wrong - do not use them to diagnose or rule out anything.
What these devices do reliably is count steps, estimate heart rate, and record roughly when you slept and for how long. Used to spot a trend over weeks, that is genuinely useful. Used as a measurement, it is not.